Butter a 9 x 13 inch baking dish. Crack eggs into a bowl and beat thoroughly. Sift together the flour, baking powder, and salt and mix with the eggs until blended. Beat in the cottage cheese, grated cheese, butter, ham, and minced onion. Pour the mixture into the prepared pan and bake for approximately 20 minutes. Sprinkle with Parmesan cheese and continue baking for an additional 15 to 25 minutes or until puffy and set in the middle, and a knife inserted in the middle comes out clean.
Vegetarian variation: Omit ham and substitute ½ cup sliced mushrooms.