1 cup white sugar
½ cup butter, melted
1 (4 ounce) package Parmesan cheese, finely grated
¾ cup sour cream
1 teaspoon baking powder
1 cup rice flour
1 tablespoon sesame seeds, or to taste
Preheat oven to 350 degrees F (175 degrees C). Beat egg whites in a glass, metal, or ceramic bowl until firm, but not stiff. Combine sugar and butter in a large bowl; beat with an electric mixer on high speed until creamy. Mix in egg yolks until well blended. Mix in Parmesan cheese gradually. Add sour cream and baking powder; beat until batter is smooth. Sift rice flour over batter; fold in with a spatula. Fold in egg whites with the spatula. Pour batter into a 9x13-inch glass baking dish. Sprinkle sesame seeds on top. Bake in the preheated oven until golden brown on top and a toothpick inserted into the center comes out clean, about 38 minutes.