The sweet tangy flavor of wild blueberries are delicious in a buttery gluten-free crust that is embellished with buckwheat and almond flour. The dough is a snap to make, since you simply mix it in a bowl and press it right into the tart pan, no chilling or rolling required.
Put the butter in a small saucepan and set over medium-high heat. Cook, swirling the pan occasionally, until the butter melts halfway. Remove from heat and swirl the pan from time to time until the butter melts completely.
Once the butter is melted, add it to the flour and stir with a fork until mixed together. Transfer to a 9-inch round tart pan and use your fingers to press the dough evenly and firmly into the bottom and up the sides of the pan. Set on a baking sheet and bake for 22 minutes.
After 22 minutes, remove the tart crust (don't worry if the edges of have slumped down into the pan a bit). Lightly grease the bottom of a metal measuring cup and use it to press the bottom and sides of the dough firmly against the pan, so it hugs the pan nicely and presses the crust back into place along the sides.
Pour the wild blueberry filling into the pan. Bake on the baking sheet until nicely browned, another 22 to 24 minutes.
Let cool for about 20 minutes before serving.