Grease 9 or 10-inch pan with melted butter; saute onion in butter. Mix Bisquick with egg; add to sauteed onion. Add 1/2 grated cheese and milk. Pour into pan. Sprinkle remainder of cheese on top. Dot with butter. Add poppy seeds.Bake at 375 degrees for 20-30 minutes. (May be frozen and reheated).
