Nectarine Slump

Name: Nectarine Slump
Ingredients: 8 tablespoons salted butter plus more for greasing casserole dish, softened; About 1 1/2 pounds ripe, sweet nectarines, pitted and quartered; 1 cup plus 1 teaspoon sugar; 2 eggs; 1 1/3 cups mascarpone; 1/8 teaspoon almond or vanilla extract; 1/4 cup all-purpose flour