01 - Preheat oven to 375°F. Lightly grease a 9x13 inch baking dish with cooking spray or a small amount of oil.
02 - Bring a large pot of salted water to boil. Add egg noodles and cook according to package directions until al dente. Drain thoroughly in a colander and set aside.
03 - Heat olive oil in a large skillet over medium heat. Add diced onion and red bell pepper if using. Sauté for 3–4 minutes until onions are translucent and peppers softened.
04 - Add ground beef to the skillet. Cook until browned completely, breaking up meat with a spatula as it cooks. Drain excess fat from the skillet.
05 - Stir in minced garlic and cook for 1 minute until fragrant. Add tomato paste, drained diced tomatoes, frozen peas if using, Italian herbs, paprika, salt, and pepper. Cook for 3–4 minutes to allow flavors to meld.
06 - Remove skillet from heat. Mix in sour cream and cream of mushroom soup until fully combined and smooth.
07 - Fold in half of the shredded cheddar cheese and the cooked egg noodles. Stir gently until noodles are evenly coated with the beef mixture.
08 - Pour the mixture into the prepared 9x13 inch baking dish. Spread evenly with a spatula. Top with remaining cheddar cheese, distributing it uniformly across the surface.
09 - Bake for 25–30 minutes until cheese is melted and golden brown, and edges are bubbling. Remove from oven and let rest for 5 minutes before serving to allow the casserole to set.