Step 1

Preheat oven to 350 degrees F (175 degrees C).

Step 2

Beat egg whites in a glass, metal, or ceramic bowl until firm, but not stiff.

Step 3

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.

Step 4

Sift rice flour over batter; fold in with a spatula. Fold in egg whites with the spatula.

Step 5

Pour batter into a 9x13-inch glass baking dish. Sprinkle sesame seeds on top.

Step 6

Bake in the preheated oven until golden brown on top and a toothpick inserted into the center comes out clean, about 38 minutes.