Heat a large skillet over medium-high heat and add the ground chuck beef, breaking it apart with a spoon as it cooks for 5-7 minutes until no pink remains. Drain off the excess fat, then stir in the tomato sauce, sugar, garlic salt, salt, and oregano. Reduce heat to medium-low and simmer for 20 minutes, stirring occasionally, to allow the flavors to meld and the sauce to thicken slightly. This long simmer develops deeper flavor complexity compared to rushing it.

While the sauce simmers, bring a large pot of salted water to a boil and cook the egg pasta for 7-9 minutes until al dente—it should still have a slight firmness when you bite it since it will continue cooking in the oven. Drain the pasta and set aside. In a separate bowl, combine the softened cream cheese, sour cream, chopped onion, and black pepper, stirring until smooth and well combined. I like to make sure the cream cheese is fully softened before mixing so there are no lumps in the final casserole.

Preheat your oven to 350°F and lightly grease a 9x13 inch baking dish. Layer half of the cooked pasta in the bottom of the dish, followed by half of the sour cream mixture from Step 2, then half of the beef sauce from Step 1. Repeat the layers with the remaining pasta, sour cream mixture, and beef sauce. Sprinkle the shredded cheddar cheese evenly over the top—I find that sprinkling it just before baking helps it melt more evenly and creates a nice golden finish. Bake uncovered at 350°F for 25-30 minutes until the cheese is melted and the casserole is heated through; the edges may bubble slightly, which is perfect.