The crostatas can be made up to 1 day ahead and stored on their pans at room temperature. Cover loosely with a clean kitchen towel. Just before serving remove towels and warm crostatas on their baking sheets in a 200°F oven for 10 minutes.
Directions:
Mix the 2 Tbs of flour and the confectioners' sugar then stir into blueberries. Set aside.
Position racks in the top and bottom thirds of the oven and heat the oven to 350° F. Line two baking sheets with parchment and sprinkle each with 1/2 teaspoon cornmeal.
Combine the remaining 1 1/2 cups flour, granulated sugar, and 2 Tbs cornmeal in a food processor and process until the consistency of fine sand. Add the butter and pulse until there are no visible pieces of butter. Add the egg yolk and water and pulse to form a soft dough, adding more water 1 tsp at a time as necessary. Gather the dough into a ball and divide into 2 even pieces.
On a well-floured surface, roll each piece of dough into an 11-inch circle and transfer to the prepared baking sheets.
Divide the blueberry filling between the circles, mounding the berries and leaving a 1 1/2-inch edge around each circle. Sprinkle any remaining sugar-flour mixture around the berry mounds. Try to get an even amount of blueberries and dry ingredients in each crostata.
Gently fold the edges of dough up over the filling, pleating as you go, to partially cover the filling. Brush the exposed dough with the egg white wash and sprinkle with sugar crystals.
Bake for 25 minutes. Rotate the sheets top to bottom and back to front. Continue baking another 25 minutes until the crusts have browned and the filling is bubbling.
Cool on the baking sheets on a rack for at least 15 minutes.
I like to garnish with a light sprinkle of fresh lemon zest.
Slice each crostata into quarters and serve warm or at room temperature.
Frozen berries can be used if fresh aren't available- thaw to room temperature and increase flour to 3 tablespoons with the confectioners' sugar.
Recipe found in CookFresh magazine, summer 2017