2 med. onions, chopped
1/4 c. butter
2 cans (6 1/2 oz. each) tuna, drained
2 c. shredded Cheddar cheese
1 c. Bisquick baking mix
1 1/4 c. milk
1/4 tsp. salt, if desired
1/8 tsp. pepper
3 eggs
2 tomatoes, thinly sliced

Heat oven to 400 degrees.

Grease square baking dish, 8x8x2 inch. Cook onions and butter in 10 inch skillet over low heat, stirring occasionally until onions are light brown. Sprinkle tuna, 1 cup of the cheese and the onions in plate.

Beat Bisquick, milk, salt, pepper and eggs with wire whisk or hand beater until almost smooth, about 1 minute. Pour into plate.