Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish and set it aside.

Bring a large pot of lightly salted water to a boil. Add the spaghetti and cook until al dente, about 12 minutes or according to the package directions.

While the pasta cooks, place a large skillet over medium-high heat. Add the ground beef and cook for 5 to 7 minutes, breaking it apart as it browns, until no pink remains.

Carefully drain any excess grease from the skillet. Pour the spaghetti sauce into the cooked beef and stir until thoroughly combined.

Drain the cooked spaghetti well and transfer it to a large mixing bowl while it is still warm.

Add the softened cream cheese, minced garlic, Italian seasoning, and garlic salt to the spaghetti. Toss and stir until the cream cheese melts and evenly coats the noodles.

Spoon a thin layer of the meat sauce across the bottom of the prepared baking dish.

Arrange the cream cheese-coated spaghetti evenly over the sauce layer.

Spread the remaining meat sauce over the spaghetti, making sure the pasta is well covered.

Sprinkle the Parmesan cheese and shredded mozzarella evenly over the top.

Bake uncovered for about 30 minutes, or until the casserole is heated through, the sauce is bubbling around the edges, and the cheese is fully melted.

Remove the casserole from the oven and allow it to rest for 5 to 10 minutes before serving.