01 - Preheat oven to 375°F. Lightly grease a 9x13 inch baking dish with cooking spray or butter.
02 - Bring a large pot of salted water to boil. Cook egg noodles according to package directions until al dente, typically 6-8 minutes. 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 become translucent and peppers soften.
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. Continue cooking for 3-4 minutes to meld flavors.
06 - Remove skillet from heat. Mix in sour cream and cream of mushroom soup until fully incorporated and smooth.
07 - Fold in half of the shredded cheddar cheese and the cooked noodles. Transfer the entire mixture to the prepared baking dish, spreading evenly.
08 - Sprinkle the remaining shredded cheddar cheese evenly over the top of the casserole.
09 - Bake for 25-30 minutes until cheese is melted and bubbly with golden-brown spots. Remove from oven and let rest for 5 minutes before serving to allow the casserole to set.