Apple Pie Bread Pudding

Name: Apple Pie Bread Pudding
Ingredients: 6 tablespoons unsalted butter, plus more for dish; 1 cup heavy cream; 1 cup whole milk; 3 large eggs; 8 ounces brioche, cut into 1-inch cubes (6 cups); ⅔ cup light brown sugar; ⅓ cup granulated sugar; 2 teaspoons pure vanilla; ½ teaspoon ground cinnamon; ¼ teaspoon ground allspice; ¼ teaspoon freshly grated nutmeg; ½ teaspoon kosher salt; 2 Granny Smith apples, peeled, quartered, cored, and sliced crosswise in ¼-inch thick pieces (2 cups); Turbinado sugar, for sprinkling (optional); Vanilla ice cream, for serving