For the filling: Combine the blueberries, ¾ cup of sugar, ⅓ cup all purpose flour, 2 large eggs, ½ cup sour cream, and ½ teaspoon vanilla.
For the crumb topping: Mix together 2 ½ tablespoons brown sugar, 2 tablespoons sugar, a pinch of nutmeg, ¼ cup melted butter, and ½ cup + 2 ½ tablespoons flour.
