Combine the almond flour, tapioca flour, salt and butter in a food processor, or use a pastry blender in a bowl. Pulse or blend until the texture of coarse meal.

Add 1 egg and pulse/mix again until dough comes together. Turn out the dough onto a piece of plastic wrap and refrigerate for at least 1 hour or up to overnight.

When ready to bake, preheat oven to 375°F.

In a medium bowl, stir together the blueberries, lemon zest and juice, maple syrup, vanilla extract, tapioca flour, and cinnamon. Toss until coated and all the dry ingredients are moistened.

Roll the dough out between two pieces of parchment paper into a circle, about 10” across. You want it thick enough to be able to hold the filling and fold up the sides.

Place the filling in the middle of the circle leaving about 2 inches around the edge empty.

Gently fold the sides up, creasing the dough together with your fingers as you go. I use the parchment to help support and fold the dough so it doesn't break.

Beat the remaining egg with a splash of water in a small bowl. Brush the outside edges of the galette with the egg wash. Stir together the cinnamon and coconut sugar and sprinkle on the egg-washed crust.

Transfer the parchment with the galette to the baking sheet and bake for 30-35 minutes, until the blueberries are burst and bubbling and the crust is golden brown. Check the galette around 20 minutes and tent with foil if the crust is browning too quickly.

Remove from the oven and let cool for 10 minutes before slicing and serving. Store leftovers in the refrigerator for up to 3 days.