Begin by bringing a large pot of water to a rolling boil and salting it generously with 1 tsp salt, then add the 8 oz spaghetti and cook until al dente according to package directions. Before draining, reserve 1/4 cup of the starchy pasta water. While the pasta cooks, heat 1 tbsp olive oil in a large skillet over medium-high heat. Add the 1 lb ground beef, breaking it up, and brown it thoroughly. Once browned, drain any excess fat, then add the 1/2 cup diced onion and cook for 3 minutes until softened. Stir in the 3 minced garlic cloves and cook for another 30 seconds until fragrant, being careful not to burn the garlic. I always make sure there is enough salt in the pasta water; salty water means flavorful pasta!

To the browned beef and aromatics, pour in the 24 oz marinara sauce. Stir in the 1 tsp dried oregano, 1/2 tsp salt, 1/2 tsp ground black pepper, and 1/2 tsp granulated sugar to balance the acidity. Bring the sauce to a gentle simmer, then reduce the heat to low, cover, and let it cook for at least 10 minutes to allow the flavors to meld. While the sauce simmers, preheat your oven to 375°F (190°C) and lightly grease your baking dish. You want to make sure your sauce gets a good simmer so the flavors develop completely; a rushed sauce is a bland sauce!

In a large bowl, combine the 8 oz room temperature cream cheese, 1/4 cup sour cream, 1/2 cup freshly grated Parmesan cheese, 1 tsp garlic powder, 1/2 tsp salt, and 1/4 tsp ground black pepper. Whisk until the mixture is smooth and lump-free. Gradually stir in the reserved 1/4 cup pasta water until the mixture is creamy and well combined. Gently fold in the drained al dente spaghetti until it is evenly coated with the cream cheese mixture. Make sure your cream cheese is at room temperature; it mixes so much smoother, preventing any lumps in your sauce!

Spread half of the rich meat sauce evenly in the prepared baking dish. Carefully layer all of the cream cheese-coated spaghetti over the meat sauce. Top with the remaining meat sauce, spreading it to cover the spaghetti completely. Finally, generously sprinkle the 1 cup shredded mozzarella cheese and the remaining 1/4 cup Parmesan cheese over the top of the dish. Cover the baking dish tightly with aluminum foil and bake for 20 minutes. After 20 minutes, remove the foil and bake for another 10-15 minutes, or until the cheese is melted, bubbly, and lightly golden. Let it rest for 5 minutes before serving to set, which makes for easier and cleaner serving.