Heat a large skillet over medium-high heat. Add the ground beef and cook, breaking it apart with a spoon, until browned and no longer pink. Drain excess grease. Stir in garlic salt, salt, and tomato sauce, mixing thoroughly. Let the mixture simmer on low heat for about 20 minutes to allow the flavors to meld. Remove from heat and cover to keep warm.

In a large pot, bring salted water to a boil. Add the egg noodles and cook until al dente, according to package instructions. Drain the noodles and rinse them under cold water to stop the cooking process. Set aside.

In a mixing bowl, combine the diced onion, sour cream, and softened cream cheese. Stir until the mixture is smooth and well blended.

Preheat your oven to 350°F (175°C). Grease a 9x13-inch casserole dish with nonstick cooking spray.

Spread half of the cooked egg noodles evenly on the bottom of the prepared dish.

Layer half of the sour cream mixture over the noodles, followed by half of the beef mixture.

Repeat the layers with the remaining noodles, sour cream mixture, and beef mixture.

Sprinkle the shredded cheddar cheese generously over the top layer. Place the casserole in the preheated oven and bake uncovered for 25 minutes, or until the cheese is melted and bubbly.

Allow the casserole to cool for a few minutes before serving to ensure clean slices. Serve warm and enjoy this comforting dish with your favorite sides.