Preheat your oven to 375°F (190°C).

In a large skillet over medium heat, cook the Italian sausage until it’s browned and cooked through, breaking it up with a wooden spoon as it cooks.

Add the chopped onion and bell pepper to the skillet, stirring them in until tender—about 3-5 minutes.

Add the minced garlic and cook for another minute.

Pour in the marinara sauce and heavy cream, stir well, and let it simmer for about 5 minutes.

Meanwhile, bring a pot of salted water to a boil and cook the tortellini according to package instructions, then drain and set aside.

In a large casserole dish, combine the sausage mixture with cooked tortellini. Stir to combine all those flavors.

Top the casserole with shredded mozzarella cheese.

Cover the casserole with foil and bake in the preheated oven for 20 minutes.

Remove the foil and bake for an additional 10 minutes or until the cheese is bubbly and golden.

Let it cool for a few minutes, then garnish with fresh basil or parsley before serving.