Okay she’s a vibe but like, IS THAT NOT THE CUTEST SPOOKY SLICE OF SOMETHING VEGETABLE RELATED, like, EVER?
I – a person with an overwhelming amount of sweet potatoes for 1 person – had the idea of making a classic southern sweet potato pie. But then, tart dreams formed, I realized I also had a plethora of purple sweet potato, and halloween spooky ooky times were near and I thought, whats the worst that could happen if I somehow turn a humble sweet potato pie into a halloween-y sweet potato tart? A deep dish tart, to be exact, so its somewhere between pie and true tart. And that’s how this beaut came to be!
But let’s get into it. There are 4 parts to this recipe: a black cocoa pâte brisée (sugarless tart crust), a spiced sweet potato pie layer, dark chocolate ganache, and a purple sweet potato egg custard top. At first read, that might sound overwhelming, but most of these come together easily. In fact, the sweet potato pie filling and the tart dough itself can both be made ahead, so day of you just have to focus on ganache and custard!
The black cocoa crust is what not only helps balance the sweetness of the overall tart, but brings in the blackness of spooky season cats, spiders, and night. Also known as the oreo cocoa, just in case you didn’t know! It’s darker and more bitter than regular cocoa, and that bitterness is what keeps four layers of sweet potato and chocolate from turning into a spooky szn sugar coma. Add it on top of the full amount of flour instead of swapping it in, because cocoa has no gluten. Then balance the hydration. Even so, this dough is a little more fragile than a normal brisee, so roll it out between two sheets of parchment and patch any tears with scraps. (That’s the beauty of a black crust!) Because of the color, you can’t tell when it’s done by looking at it, so go by the timer and look for a bottom that’s dry and matte instead of shiny. Before the filling goes in, brush the hot crust with the egg white left over from the sweet potato pie layer and give it two more minutes in the oven. That thin seal keeps the bottom from going soggy under all that filling, and really does make a difference! Plus, no waste on the egg white.
A note on edges: leave yourself some extra dough, fold it under, and press it onto the rim of your dish. Pastry shrinks even when pre-chilled and this tart needs every bit of height it can get. (I made mine in a deep dish pie plate, which is how we ended up in pie-tart limbo. If it works, it works okay??)
The orange layer is where, as I mentioned, the classic sweet potato pie lives. Roast the orange sweet potato instead of boiling it first, so the flavor concentrates instead of getting waterlogged. Then it gets ginger, cinnamon, nutmeg, allspice, cloves, and a pinch of black pepper, which is the part nobody can name but everybody would miss. It’s sweetened with maple instead of brown sugar, and between that and all the spice it bakes up a deep orange rather than neon. Which is exactly where it should land color wise in my opinion anyways. Bake it until the edges are set and the center barely barely wobbles, then let it cool completely and get cold in the fridge. This also as I previously mentioned can easily be your make-ahead layer. Do the crust and this layer the day before, and you’ve already done the hard part imo!
The ganache is standard and the thin dark line between the orange and the purple, and it’s there for looks and flavor. I mean, who doesn’t like an added layer of chocolate in a dessert? 2 things matter here and then we will move on. First, if you want to keep the whole tart refined sugar free as I have and suggest, use a dark chocolate sweetened with coconut sugar, because most chocolate isn’t. Second, this ganache is intentionally soft, with more cream than usual, so it slices along with the layers around it instead of cracking into shards. Let it cool until it’s lukewarm, pour it over the cold orange layer, and chill it about twenty minutes until it sets. That’s pretty much it for this layer!
Now last but not least, the purple top. Bake purple sweet potato for too long and it goes from purple to dusty mauve, which is not the look for Halloween we are aiming for. Because of that, this layer never sees the oven. Instead, I made it an egg custard that’s cooked on the stovetop with cornstarch, blended with steamed purple sweet potato, then poured on top to set in the fridge. It adds time, but the steaming keeps the color brighter than roasting does. I also added in lemon juice and zest at the end to push the color toward a true bright violet, since purple sweet potato changes color with acidity. Yes, just like red cabbage, and other purple vegetables with the same chemical compound! Add the juice a little at a time, and enjoy seeing streaks of pink appear before mixing in!
Cool it slightly to not melt the ganache below, and pour it over before chilling. I say 4 hours minimum, but I truly do want to encourage you to leave it untouched in the fridge overnight if you can. I say this for those like me who genuinely are making this so that you get the gorgeous clean cuts on each of the pieces as it is served. You put in all that hard work, a few more hours of patience to make it perfect is worth it!! When it’s ready, slice it straight from the fridge with a knife run under hot water and wiped dry, and wipe it again between every cut. That’s how you get the most perfect clean stripes.
It keeps covered in the fridge for up to 3 days, although it might even push a little farther than that. I do recommend though to not freeze it, as the top custard weeps when it thaws and it won’t look as good post-frozen.
So, long story short: Is it a little bit of a project? Yes. Is it worth it when you cut in and there’s black, orange, and purple spooky halloween in dessert form goodness staring back at you? Also YES! Now go make something spooky out of a vegetable, and enjoy! Happy Halloween!
Halloween Spooky Sweet Potato Tart
Equipment
- 9-inch deep tart pan with removable bottom (about 1 ¾” deep)
- Food processor or pastry cutter
- Rolling Pin
- Parchment paper and pie weights (or dried beans)
- Baking sheet
- Steamer basket and pot
- Medium saucepan
- Whisk
- Blender
- Small heatproof bowl
Ingredients
Black cocoa pastry crust
- 1 ½ cups 190g all-purpose flour, plus more for patching
- ¼ cup 20g black cocoa powder
- ½ tsp fine sea salt
- 10 tbsp 142g cold unsalted butter, cubed
- 5 to 8 tbsp ice water
- 1 egg white left over from the orange layer, lightly beaten
Spiced orange sweet potato layer
- 1 ¼ cups mashed roasted orange sweet potato about 1 lb raw
- ½ cup unsweetened evaporated milk
- ⅓ cup maple syrup
- 1 large egg plus 1 egg yolk save the white for the crust
- 2 tbsp unsalted butter melted
- 1 tsp ground ginger
- ½ tsp ground cinnamon
- ½ tsp freshly grated nutmeg
- ½ tsp ground allspice
- ⅛ tsp ground cloves
- Pinch of black pepper
- ½ tsp fine sea salt
- 1 tsp vanilla extract
Soft ganache layer
- 2 oz coconut-sugar-sweetened dark chocolate finely chopped
- ⅓ cup heavy cream
- Pinch of salt
Purple sweet potato custard
- 1 ¼ cups steamed purple sweet potato mashed (about 1 lb raw)
- ⅔ cup whole milk
- ⅓ cup heavy cream
- ⅓ cup maple syrup
- 1 large egg
- 1 ½ tbsp cornstarch
- ⅛ tsp ground cardamom
- ¼ tsp fine sea salt
- 1 tbsp unsalted butter
- ½ tsp vanilla extract
- 1 to 1 ½ tsp fresh lemon juice
- ½ tsp finely grated lemon zest
Instructions
- Make the dough. Pulse the flour, black cocoa, and salt in a food processor until evenly combined. Add the cold butter and pulse until the biggest pieces are pea-sized. Drizzle in 5 tbsp ice water and pulse just until the dough clumps when pinched, adding more water a tablespoon at a time if it’s dry. Cocoa soaks up water, so it will likely need more than plain pastry. Press into a disk, wrap, and chill at least 1 hour.
- Cook the potatoes while the dough chills. Heat the oven to 400°F. Prick the orange sweet potato and roast it on a baking sheet for 45 to 50 minutes, until completely soft. Meanwhile, peel and cube the purple sweet potato and steam it 15 to 20 minutes, until a fork slides through. Roasting the orange one deepens the flavor. Steaming the purple one protects the color. Mash each separately, measure 1 ¼ cups of each, and let them cool.
- Roll and shape the crust. Roll the dough between two sheets of parchment into a 13-inch round. Peel off the top sheet, flip the dough into the tart pan, and peel off the second sheet. Press the dough into the corners and up the sides without stretching it, patch any tears with scraps, and trim the excess. Prick the bottom with a fork and freeze 30 minutes. Set the oven to 375°F.
- Blind bake. Line the cold crust with parchment and fill it with pie weights. Bake 20 minutes, then remove the parchment and weights and bake 8 to 10 minutes more. You can’t judge doneness by color here, so look for a bottom that looks dry and matte instead of shiny. Brush the hot crust with the beaten egg white and return it to the oven for 2 minutes to seal it, which keeps the bottom from going soggy. Lower the oven to 325°F.
- Make the orange layer. Blend or whisk the orange sweet potato, evaporated milk, maple syrup, egg, yolk, melted butter, all the spices, salt, and vanilla until completely smooth. Pour it into the warm crust and smooth the top.
- Bake. Bake at 325°F for 35 to 45 minutes, until the edges are set and the center has only a slight wobble. Since you can’t see the crust edges browning, cover them with strips of foil about halfway through. Cool on a rack 1 hour, then refrigerate 30 minutes so the surface is cold before the ganache goes on.
- Make the ganache. Heat the cream until steaming, pour it over the chocolate and salt, and let it sit 2 minutes. Stir until smooth, then cool about 10 minutes, until lukewarm but still pourable. Pour it over the chilled orange layer and tilt the pan to spread it edge to edge. Chill 20 minutes, until set.
- Start the purple custard. In a bowl, whisk the maple syrup, egg, cornstarch, cardamom, and salt until smooth. Heat the milk and cream in a saucepan until steaming. Slowly whisk half of the hot milk into the egg mixture, then pour it all back into the pan.
- Cook it until it means it. Whisk constantly over medium heat until the custard thickens and bubbles, then keep whisking a full minute more so it sets properly in the fridge.
- Blend. Add the hot custard, purple sweet potato, butter, and vanilla to the blender and blend until silky, venting the lid. Blend in the lemon zest and 1 tsp lemon juice. Taste it, and add the last ½ tsp of juice if the color looks dull or it tastes flat.
- Cool it slightly, then layer. Let the custard sit 10 to 15 minutes, stirring now and then, until warm but no longer hot. Pour it slowly over the back of a spoon onto the set ganache and smooth the top.
- Chill. Press plastic wrap directly onto the surface and refrigerate at least 4 hours, or overnight, until firm enough to slice.
Notes
Plain pastry crust: Leave out the black cocoa and start with 4 tbsp ice water. You’ll get a golden crust instead, and the ganache still gives you a black stripe.
A store-bought pie dough works, but most rounds are too small for a deep tart pan. Check that yours rolls to 13 inches, or plan on piecing it.
Heavy cream can replace the evaporated milk in the orange layer. It comes out a little richer and a little less classic. Optional add-ins
Spiderweb top: Thin ¼ cup sour cream with 1 tbsp cream and 1 tsp maple. Right after pouring the purple layer, pipe concentric circles on top and drag a toothpick from the center outward. Tips
Check the potato. Stokes Purple (purple skin, purple inside) gives true purple. Okinawan (beige skin) comes out pale lavender. If the label just says “purple,” cut one open before you commit.
The black cocoa dough is a little more fragile than plain pastry. Rolling it between parchment makes it much easier, and patches won’t show once it’s baked.
Keep everything cold when making the dough. If it gets soft or sticky while you roll it, put it back in the fridge for 10 minutes.
For the cleanest stripes, slice cold with a hot, dry knife and wipe it between every cut.
The steps can easily be split across 2 days for ease. Make the dough, crust, and orange layer one day, then do the ganache and purple layer the next. Storage
Keep covered in the fridge for up to 3 days. Don’t freeze it: the cornstarch custard weeps when thawed.