Bring a large pot of lightly salted water to a boil. Add penne and cook, stirring occasionally, until tender yet firm to the bite, 8 to 10 minutes. Drain and set aside.

While the pasta is cooking, melt butter in a large pot over medium heat. Add onion and bell pepper; sauté until translucent, about 5 minutes. Add ground pork and cook until evenly browned and crumbly, 7 to 10 minutes. Drain excess fat and transfer to a bowl.

Pour spaghetti sauce into the same pot and heat over medium heat until bubbling, 3 to 5 minutes. Add cooked penne and pork mixture, then stir in sour cream. Cook until heated through, about 5 minutes.