In a large deep skillet or Dutch oven, cook the sausage over medium heat until lightly browned, about 4–5 minutes
Add diced bell pepper. Cook 2–3 minutes until softened
Stir in uncooked pasta, marinara sauce, Italian seasoning, garlic powder, and 1 ½ cups water or broth. Bring to a boil
Reduce heat to medium-low, cover, and simmer 10–12 minutes, stirring occasionally, until the pasta is tender and most of the liquid is absorbed.
Stir in the 2-3 tbsp cream cheese, mozzarella, and cheddar or parm cheese until creamy
Cover for 2–3 minutes to let everything meld together. Serve hot, cheesy, and gooey.