01 -
Bring a large pot of salted water to a boil. Cook the spaghetti until just shy of al dente, about 2 minutes less than the package directions. Drain and set aside.
02 -
Heat a large skillet over medium-high heat. Add the ground beef and cook, breaking it up, until deeply browned and no pink remains, 5 to 7 minutes. Drain excess fat. Stir in the marinara sauce, Italian seasoning, and garlic powder. Simmer for 5 minutes.
03 -
In a large bowl, beat the softened cream cheese with sour cream and Parmesan until completely smooth. Add the hot spaghetti and toss until every strand is coated with the mixture.
04 -
Lightly grease a 9x13-inch baking dish. Spread half the meat sauce across the bottom. Add the spaghetti mixture and spread into an even layer. Pour the remaining meat sauce over the top.
05 -
Preheat the oven to 350°F (175°C). Scatter the shredded mozzarella evenly over the top. Bake uncovered for 30 minutes, until the cheese is melted and the edges are bubbling. Let rest for 10 minutes before serving.