Preheat the oven to 375°F. Lightly coat a 9 × 13-inch baking dish with nonstick cooking spray.
Bring a large pot of salted water to a boil. Cook the egg noodles until just al dente according to the package directions. Drain well and set aside.
Add the ground beef and diced onion to a large skillet over medium-high heat. Cook for 6–8 minutes, breaking the beef into crumbles, until browned and the onion is tender. Drain excess grease.
Stir the garlic into the beef and cook for about 30 seconds, just until fragrant.
Add the tomato sauce, diced tomatoes, tomato paste, Italian seasoning, paprika, salt, and black pepper. Stir well and simmer for 5 minutes.
In a large bowl, mix the softened cream cheese and sour cream until smooth. Stir in 1 cup of the shredded cheddar.
Add the drained noodles to the creamy cheese mixture and gently toss until evenly coated.
Spread half of the creamy noodles across the bottom of the prepared baking dish. Spoon half of the beef mixture evenly over the noodles.
Repeat with the remaining noodles and beef mixture. Sprinkle the remaining 1 cup cheddar and the mozzarella evenly over the top.
Bake uncovered for 20–25 minutes, until the casserole is heated through and the cheese is melted and bubbling around the edges.
Remove from the oven and let the casserole rest for 5–10 minutes. Garnish with chopped parsley, if desired, and serve warm.