Peach and Berry Cobbler

Name: Peach and Berry Cobbler
Ingredients: 6 tablespoons cold unsalted butter, cut into small pieces, plus more for the dish; 1 1/2 cups all-purpose flour, plus more for dusting; 1/3 cup granulated sugar; 1 teaspoon baking powder; 1/4 teaspoon ground nutmeg; 1/4 teaspoon salt; 1/2 cup heavy cream, plus more for brushing; Coarse sugar, for sprinkling; 3 pounds peaches (about 9 medium), pitted and sliced 1/4 inch thick; 2/3 cup granulated sugar; 1/4 cup cornstarch; Grated zest and juice of 1/2 orange; 1 teaspoon pure vanilla extract; 1 6-ounce container raspberries; 1 6-ounce container blueberries