Fry hamburger and chopped onion together; drain and put mixture in an ungreased 9x13 inch baking pan. In a separate bowl, put the frozen mixed vegetables, garlic powder, cream of chicken soup and 1 cup of the milk. Mix well and pour over the hamburger-onion mixture. Mix together the Bisquick and remaining 1 1/2 cup of milk (will be thin). Pour over the mixture in the pan. Bake at 450 degrees until crust is golden brown. (It took about 40 minutes for me, but ovens vary).

You could use diced chicken, turkey, or ham, or tuna instead of the ground beef.