Beat 3 eggs; add 1 cube melted butter, 1 1/2 cups milk, and 1 scant cup Bisquick. Pour into greased 8 x 12 inch Pyrex pan. Sprinkle 1 cup shredded Swiss cheese and 1 cup crisp bacon bits (or ham) and 1/2 cup sauteed onion on batter. Pat down into surface of batter and bake 35 minutes at 350 degrees. Cut into squares. Can be baked ahead and warmed up with foil over top.