Heat a medium sized skillet on the stove-top over medium high heat. Add the ground beef, onion and bell pepper. Cook and crumble the ground beef. Drain off the excess fat.
Add the cheddar cheese soup and milk to the pan and stir and cook until the well mixed. Turn off the heat and set aside.
In a medium mixing bowl, combine the all-purpose baking mix and water and stir until mixed. Pour batter into the bottom of a 3.5 quart casserole slow cooker OR 6 quart slow cooker and spread it evenly.
Add the ground beef mixture to to the top of the batter and spread evenly.
Cover and cook on HIGH for 3 to 4 hours or until the baking mix mixture is cooked through.
Spoon casserole out onto plates and top with shredded cheddar cheese before serving.