Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish.
Bring a large pot of salted water to a boil. Cook the egg noodles until al dente according to the package directions, then drain and set aside.
Heat a large skillet over medium-high heat. Add the ground beef and cook until browned, breaking it apart with a spoon. Ensure the meat reaches a safe internal temperature of 160°F (71°C) measured with a food thermometer.
Drain any excess fat from the skillet. Stir in the tomato sauce, season with kosher salt and black pepper, and reduce the heat to a simmer while you prepare the remaining ingredients.
In a medium bowl, mix the sour cream, cottage cheese, and sliced green onions. Season with a pinch of salt and pepper. Stir the drained egg noodles into this cheese mixture until well coated.
Spread half of the coated noodle mixture into the prepared baking dish. Spoon half of the ground beef sauce over the noodles, then sprinkle with half of the grated cheddar cheese.
Repeat the layers with the remaining noodles, beef sauce, and cheddar cheese.
Bake uncovered for 20 minutes, or until the cheese is melted and the edges are bubbling. Let the casserole rest for 5 minutes before serving.