Preheat your oven to 350°F and spray your baking dish so nothing sticks when you bake it later.
Boil spaghetti in salted water like the box says until it's just tender, then drain all the water out really well.
Cook ground beef in your skillet on medium-high heat, breaking it up as you go, for 8-10 minutes until it's all brown.
Pour out extra grease, then mix in marinara sauce, garlic powder, and Italian seasoning, and let it bubble on low for 5 minutes.
Mix softened cream cheese and sour cream in a bowl until it's smooth with no lumps left in it at all.
Put half the cooked spaghetti in your baking dish as the first layer of your yummy casserole.
Spread the cream cheese mix on top of the spaghetti, making sure it goes all the way to the edges of the dish.
Pour your meat sauce over the cream cheese layer and spread it out, then put the rest of the spaghetti on top.
Sprinkle mozzarella and Parmesan cheese all over the top so it covers everything and will get nice and golden.
Bake for 30-35 minutes until the cheese is melted, bubbly, golden brown, and everything is hot all the way through at 165°F.
Take it out and let it sit for 10 minutes so the layers set up and you can cut nice neat pieces.