Add ground beef, sausage, onion and green pepper to a large saucepan over medium heat. TIP: If you don't want to add an extra item to your grocery list, you could easily substitute another pound of ground beef for the sausage.
Cook until beef and sausage are browned and cooked through and onion and green pepper are softened.
Drain beef mixture and pour into 9x13 casserole dish.TIP: Want to make this a one pot meal? No problem! Simply drain the beef mixture and continue with the recipe in the same oven proof saucepan. I love using my Le Creuset Round Brasier for recipes like this.
Layer pepperoni slices evenly over beef mixture.TIP: Love other pizza toppings? Feel free to substitute! Canadian bacon would be a great swap for the pepperoni if it's one of your faves.
Pour pizza sauce over pepperoni and spread into an even layer.
Top with cheddar cheese slices. You may have to halve slices to create a single layer.
In a medium bowl, add baking mix, milk, garlic powder and Italian seasoning.TIP: In a pinch you could use Bisquick instead of my Homemade Baking Mix, but I promise mine tastes better and is worth the minimal effort involved!
Stir together until just combined.TIP: You only want to stir together until you can no longer see any dry ingredients. Stir too much and you'll be left with a tough biscuit topping. And really, nobody wants that!
Drop biscuit mixture onto cheese and spread into an even layer. TIP: I find it easiest to use my hands when adding the biscuit mix to the top of the casserole so that none of the other layers below shift.
Bake at 450 degrees for 15 minutes or until top is golden. Serve upside down.