Cook and stir beef and onion in large skillet until beef is cooked through and scrambled; drain. Stir in Manwich. Heat through.
Remove from heat and set aside. Generously grease a 12 cup bundt cake pan. Mix together the Bisquick, milk, margarine and eggs; beat vigorously for 30 seconds. Spread 2 cups of the batter in bottom and about 2 inches up sides and center of pan(around tube). Spoon beef mixture evenly onto center of batter. Drop remaining batter by teaspoonfuls about 1/2 -inch apart onto beef mixture and spread to cover meat. Bake in 375^ oven about 25 minutes until light brown and firm. Invert on serving plate. Kids usually like this.
Just think of all the mixtures you can put inside of this batter! How about a Reuben, Want the recipe. Let me know. I got it.