In a large pot, bring water to a boil and season it with salt. Add the tortellini and cook according to package instructions, usually about 3-5 minutes until al dente. Once cooked, drain and set aside in a large mixing bowl.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add chopped yellow onion and sauté for 3-4 minutes until softened. Then, add the ground beef and Italian sausage, cooking for 6-8 minutes until browned. Stir in minced garlic and Italian seasoning, letting the flavors meld.

Pour the pizza sauce over the sautéed meat mixture, stirring well to ensure everything is coated. Gently fold in the cooked tortellini until evenly mixed. Reduce the heat to low and let the mixture simmer for about 5 minutes.

Preheat your broiler. Transfer the tortellini mixture into a baking dish and sprinkle a generous layer of mozzarella cheese on top. Place the dish under the broiler for about 3-5 minutes, until the cheese is melted and bubbly.

Remove the dish from the oven and cool for a few minutes before serving. Garnish with chopped herbs like basil or parsley if desired.