Yield 15 bars
Crumb crustand topping:
4 cups potato starch
3 cups almond flour
1½ cups oil
½ teaspoon cinnamon
1 heaping tablespoon potato starch
¾ cup water
10 red plums, diced
½ cup sugar
Juice of 1 lemon
Cinnamon, for dusting
Confectioners’ sugar, for dusting
Preheat oven to 350°F. Line a 9×13-inch baking dish with parchment paper.
Prepare the crumb crust and topping: In a bowl, mix together the potato starch, almond flour, oil, eggs, and cinnamon.
Transfer 2 cups of the crumb mixture to the baking dish and press down firmly to form a crust. (Reserve the remaining crumbs for step 6.) Bake for 10 minutes, then set aside.
Prepare the plum filling: In a small bowl, whisk together the potato starch and water to combine. Pour into a saucepan. Add the plums, sugar, and lemon juice.
Bring to a boil, then reduce heat to low and cook for 10 minutes, until plums are just tender and the mixture becomes gelled. Spread over the baked crust in an even layer.
Sprinkle liberally with the reserved crumbs from step 3. (You won’t need it all. Save the leftovers to top any dessert before baking!)
Bake 10–15 minutes, then let cool and cut into bars. If you like, dust
with cinnamon and confectioners’ sugar before serving.