Preheat oven to 350 degrees F. Butter the sides of a 9-inch springform pan and dust with corn flour. Line the base with parchment paper.
After pitting the cherries, cut them in half. Add blueberries to cherries and set aside.
Mix the almond flour, 1/2 cup of corn flour, tapioca starch, baking powder, and salt together in a medium bowl.
Cream the butter and sugar with a mixer in a large bowl until the mixture is pale in color. Add the eggs, one at time, beating after each addition. Add the vanilla.
Stir in half of the almond flour mixture into the wet ingredients until combined. Repeat with remaining almond flour mixture. Transfer the batter into the prepared springform pan. Smooth the top to make it even.
Toss the cherries and blueberries with one tablespoon of corn flour. Place the cherry-berry mixture on the outer two thirds of top, leaving the center portion uncovered. (Fruit in the middle of the cake might keep the center too wet.)
Bake for around 50 minutes, or until a toothpick inserted into the center comes out clean.
Allow cake to cool in pan for 10 minutes. Place on a wire rack and release the sides of the pan. Remove springform ring.
Let cake cool completely.
When ready to serve, dust with powdered sugar, if desired.