Heat the olive oil in a large skillet over medium-heat. Cook the ground beef with the garlic, until it's completely browned, then drain off the excess fat.
While you are cooking your ground beef is a good time to be cooking your pasta, then everything will be ready at the same time. Follow the package directions for that.
Pour in the marinara sauce. Then add the Italian seasoning and salt and pepper to taste. Stir, reduce the heat to low and simmer for 15 minutes.
Remove from heat and add the sour cream. Stir to combine. Then add the mozzarella and the cooked pasta. Stir to combine.