Heat a large skillet over medium-high heat. Add the ground beef and cook until browned and crumbly. Drain excess grease.

Stir in the garlic salt, salt, tomato sauce, and white sugar. Mix until well combined.

Simmer the beef mixture for about 20 minutes. Remove the skillet from the heat and cover.

In a large pot, bring salted water to a boil. Cook the egg noodles until al dente.

Drain the noodles and rinse with cold water to stop the cooking.

Preheat the oven to 350°F (175°C). Grease a 9×13-inch casserole dish with cooking spray.

In a mixing bowl, combine the diced onion, sour cream, and softened cream cheese until smooth.

Layer half of the cooked noodles in the bottom of the prepared casserole dish.

Spread half of the sour cream mixture over the noodles.

Spoon half of the beef mixture over the creamy layer.

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

Sprinkle the top generously with shredded sharp Cheddar cheese.

Bake for about 25 minutes, or until the cheese is melted and bubbly.

Remove from the oven and let the casserole rest for a few minutes before serving warm.