Add onion in and cook for a few minutes, then add the ground beef and sausage. Add tomato sauce in and stir fry until the meat become brown. Season with salt and pepper to taste. Remove from heat and let it cool.
Meanwhile, cut the top of each bell pepper and remove seeds.
Once the meat is cool, combine it with 1 cup of shredded Gouda cheese.
Fill each pepper with the meat-cheese mixture then top with more shredded Gouda.
Transfer the peppers into the baking pan. Bake 20-25 minutes in the preheated oven until the cheese is melted. Enjoy!