These mini blueberry galettes are so fun to make! The blueberry filling is perfectly sweet and the galette dough is flaky and tender.
Make the pie crust: Combine flour, sugar, and salt in a food processor by pulsing a few times. Add the butter cubes and pulse a few times until a pea sized coarse meal forms. Add the buttermilk and continue to run the food processor continuously for several seconds or until a dough forms. Transfer dough to a clean surface and divide into 6 equal parts, forming disks. Wrap each disk with plastic and refrigerate for at least one hour or overnight.
Preheat oven to 400 degrees.
Meanwhile, make the blueberry mixture: in a large bowl, combine the blueberries, granulated sugar, cornstarch, lemon zest, lemon juice, vanilla extract, and a pinch of salt. Set aside.
On a clean floured surface, roll each dough disk into an 8 inch round circle. If the dough is too hard, wait 15 minutes.
Add about 2/3 cups of the blueberry mixture onto the center of the dough circle, leaving about 1 inch at the borders. Fold in the borders. Transfer the galettes to 2 sheet pans lined with parchment paper.
Make the egg wash by combining the beaten egg with the milk.
Brush the edges of the galettes with egg wash and top with some sanding sugar or turbinado sugar.
Bake about 25 minutes or until bubbly and golden brown. Let cool for a few minutes and enjoy!