In a large pot, heat olive oil over medium heat. Add chopped pepperoni and cook until crispy, about 5 minutes.
Stir in onion, celery, carrot, and garlic. Sauté until vegetables are soft, about 3–4 minutes.
Add ground beef and sausage. Cook, breaking up the meat, until browned, about 10 minutes.
Mix in dried oregano, salt, pepper, and tomato paste. Cook for 3–4 minutes.
Pour in marinara sauce and water (or milk). Stir well and bring to a gentle simmer.
Simmer uncovered for 10–15 minutes, stirring occasionally, until sauce thickens.
Stir in cream cheese and pesto until melted and fully incorporated.
While sauce simmers, cook tortellini according to package directions. Drain and return to pot.
Ladle sauce over tortellini, add Parmesan cheese, and toss to coat evenly.
Serve immediately, garnished with fresh herbs and more Parmesan.