Preparation

• Mix the blueberries, 3 Tbs. of the flour, and the confectioners’ sugar in a medium bowl. Set aside.
• 架在顶部和底部的三分之二oven and heat the oven to 350°F. Line two rimmed baking sheets with parchment.
• Combine the remaining 1-1/2 cups flour, granulated sugar, and 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 work 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. Fold the edges 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 the raw sugar.
• Bake for 25 minutes. Rotate the sheets top to bottom and back to front. (If there is any white flour mixture showing, carefully spoon a little of the blueberry juices over to cover.) Continue baking until the crusts have browned and the filling is bubbling, about 25 minutes more. Cool on the baking sheets on a rack for at least 15 minutes or to room temperature.

Serve

• Slice each crostata into quarters and serve with scoops of the ice cream on top.

Make Ahead Tips

The crostatas can be made up to 1 day ahead and stored on their baking sheets at room temperature, covered loosely with a clean kitchen towel. Just before serving, warm the crostatas on their baking sheets in a 200°F oven for 10 minutes.

In order for the ice cream to readily melt and mingle with the crostata, either the crostata should be a bit warm from the oven or the ice cream should be slightly soft. If you’ve made both elements ahead and the ice cream is very hard, let it sit briefly at room temperature.