Preparation - In a medium skillet, brown the ground beef and onions. Drain off the fat. Add salt and pepper. Spoon the mixture into the bottom of 9" deep-dish pie pan. Sprinkle the cheddar cheese on top. Mix the milk, eggs and baking mix together in a blender or food processor and process until smooth. Pour the mixture over the meat and cheese in the pie dish. Bake in a preheated oven at 350° for 30 minutes. Let stand for 5 minutes before serving.