3tablespoons(30 g) potato starch (I think tapioca starch would work too)
½cup(100 g) packed organic light or dark brown sugar
½teaspoonfine sea salt
3tablespoons(40 g) cold unsalted butter, cubed
grated zest of ½ large lemon
2tablespoonsmilk of your choice
1large egg, separated
¼cup(50 g) organic granulated sugar (decrease to 2 tablespoons if your jam is very sweet)
zest from ½ large lemon
12ounces(about 1 ½ cups, 340 g) whole milk ricotta cheese (I prefer Bellwether Farms basket dipped ricotta)
big pinch salt
1 ¼cupscherry or berry jam, or another jam that you love the flavor of
a handful of sliced almonds, for garnish
Make the crust:
Place a 9- or 10-inch tart pan with a loose bottom and 1.25-inch high sides on a rimmed baking sheet. Rub the tart pan well with the soft butter or spray with cooking oil, taking care to grease the fluted edges of the pan.
In the bowl of a food processor, combine the oat, sweet rice, and almond flours with the potato starch, brown sugar, baking powder, baking soda, and salt. Add the cold butter, egg, vanilla extract, and lemon zest and blend until the butter is incorporated, about 30 seconds. Drizzle in the milk and process until the dough comes together. Gather the dough into a ball and press evenly into the bottom and up the sides of the pan; it will take a few minutes to make it look pretty. Chill the dough until firm while you prepare the filling.
Make the filling:
Position a rack in the upper third of the oven and preheat to 350ºF.
Combine the egg yolk, brown sugar, vanilla, and lemon zest in a medium bowl or the bowl of a stand mixer and beat with a handheld mixer or the paddle attachment until thick and foamy, 5 minutes. Beat in half of the ricotta until just combined, then beat in the remaining ricotta.
In a separate, completely clean bowl or the bowl of a stand mixer, whip the egg white and salt with a whisk or the whip attachment until soft peaks form. Fold one-third of the beaten egg white into the ricotta mixture, then fold in the remaining egg white.
Spread all but 3 or 4 tablespoons of the jam in the bottom of the chilled tart crust. Scoop the ricotta mixture on top and spread into an even layer. Drop spoonfuls of the remaining jam over the ricotta and swirl with the tip of a chopstick. Decorate the edges of the tart with the sliced almonds.
Bake the tart until the filling is puffed and somewhat set and the edges of the tart are golden, 35-45 minutes; the crust will still be soft but a toothpick inserted into the crust should come out clean or with a few moist crumbs. Take care not to overbake; this crust is more similar to a cookie or cake and wants to be kept moist.
Let the tart cool completely. Release the sides from the pan, cut into wedges, and serve at room temperature. The tart can be made a day ahead; chill until ready to serve. Leftovers keep for up to 3 days refrigerated airtight.
Lightly adapted from Naturally Vegetarian.If gluten isn’t an issue, you can make this with ½ cup whole wheat flour in place of the oat flour as per the original recipe, adding just enough milk to form a dough that holds together but isn’t sticky.This tart filling is only as good as the ricotta and jam you use. Look for artisanal whole-milk ricotta and a jam that tastes bright and has some tartness or acidity. I used a strawberry, peach, and raspberry jam that was divine. Apricot, tart cherry, plum, and blackberry would also be good options, as would the rhubarb puree from Alternative Baker.Nutritional values are based on one in ten servings.