Chocolate and Butterscotch Bread Pudding

Name: Chocolate and Butterscotch Bread Pudding
Ingredients: 1 to 2 tablespoons unsalted butter; 1 1/2 cups heavy cream; 1/2 cup sour cream; 1/2 cup maple syrup; 1 cup packed dark brown sugar; 1/2 teaspoon ground cinnamon; 1/2 teaspoon salt; 4 eggs; 8 cups diced day-old bread (1-inch dice); 1/2 cup bittersweet chocolate chips; 1/2 cup butterscotch chips; 7 egg whites; Pinch salt; 1/4 teaspoon cream of tartar; 1 1/4 cups granulated sugar; 1/2 pint vanilla ice cream; 2 tablespoons bourbon; 1/4 teaspoon freshly grated nutmeg