Boil the spaghetti: Cook the spaghetti noodles in a large pot of salted water until just tender, about 8-10 minutes. Drain and toss with 1 tablespoon of butter.

Cook the meat: In a large skillet over medium heat, brown the ground beef until fully cooked. Drain any excess fat and stir in the marinara sauce, minced garlic, and Italian seasoning. Simmer for about 5 minutes.

Mix the creamy filling: In a bowl, combine softened cream cheese with sour cream, seasoning with salt and pepper. Add warm pasta water if the mixture is too thick.

Layer the casserole: Spread half of the spaghetti noodles in a 9x13 baking dish, dollop the cream cheese mixture over it, and add the remaining spaghetti noodles on top.

Add the meat sauce: Pour the meat sauce over the pasta layers and top with shredded mozzarella and Parmesan.

Bake: Preheat your oven to 350°F (175°C) and bake for 25-30 minutes until hot and bubbly, covering initially to prevent drying. Uncover to allow the cheese to brown.

Let it set: Allow the casserole to sit for about 10 minutes before slicing.