Adapted from the Frugal Gourmet TV series
Preheat oven to 400º F
Sauté onion in skillet with butter or margarine until wilted and turning clear (or starting to brown if you wish).
Beat eggs in large bowl, add flour, baking powder, and salt. Stir in cottage cheese and 1/2 the amount of jack cheese. Gently stir in onions and any other vegetables (if desired). Sprinkle remaining jack cheese on top.
Pour into 9" x 13" (or similar size) greased baking dish. Bake for 15 minutes at 400º. Reduce heat to 350º and bake for another 30 minutes or until top is golden and puffy.