1 lb. peaches, sliced
1 cup plus 2 Tbsp. sugar
1 1/2 cups flour
1 tsp. cream of tartar
1/2 tsp. baking soda
1/2 tsp. corn starch
1/4 tsp. salt
1/2 cup milk
1 tsp. vanilla
1/2 cup (1 stick) butter, softened
2 eggs, separated
Preheat the oven to 350°F.
Spread the peaches into the bottom of a 9-inch baking dish. Sprinkle with 2 tablespoons of the sugar. Let sit.
Combine the flour, cream of tartar, soda, cornstarch and salt in a medium bowl.
Combine the milk and vanilla in a small bowl. Set aside.
Cream together the butter and remaining 1 cup sugar in a medium bowl. Add the egg yolks one at a time, beating to incorporate completely. Add the milk and flour mixtures in alternating additions, beating continuously.
Beat the egg whites until soft peaks form. Fold into the batter and pour over the peaches. Spread over the peaches evenly and bake until a skewer comes out clean, about 1 hour. Let cool slightly before inverting onto a large platter.