Set a large soup pot or Dutch oven over medium high heat, add some olive oil and the sliced smoked sausage. Cook 3 to 4 minutes or until browned how you prefer and set them aside.

Note: Smoked sausage is already cooked, we just want to char or brown them for extra flavor.

Set the same pot over medium heat and add more olive oil, the spinach, mushrooms, kosher salt, pepper, and crushed red pepper flakes. Cook 5 to 6 minutes, stirring a few times. Remove and set aside with the sausage.

Rinse out the same pot with water and set it back on the stove on high. Add the butter and heavy cream. Once that comes to a boil, reduce the heat to medium low and simmer 5 to 6 minutes. Add the pesto and parmesan and cook 2 to 3 more minutes, stirring a few times.

Add the uncooked tortellini, sausage, spinach, and mushrooms to the pot with the pesto cream sauce and gently stir until evenly mixed. Pour into a 9x13 casserole dish. Top with the mozzarella cheese and bake in a 350-degree oven for 20 to 30 minutes.

Serve with fresh basil for garnish if desired.