Mix flour, cornmeal, sugar, baking powder, and salt in a large bowl. Make a well in the middle of the dry ingredients.
Add the sour cream, cottage cheese, beaten egg, and vegetable oil. Stir to incorporate ingredients.
Fold thawed chopped broccoli and minced onion into mixture. Bake in an 8 or 9-inch square pan sprayed with nonstick spray in a 375-degree oven for 30 to 35 minutes or until a toothpick inserted in center comes out clean.