Preheat oven to 350°; spray 13 x 9-inch baking dish with cooking spray. Prepare spaghetti as label directs for al dente spaghetti; drain, return to saucepot and cover to keep warm.
Heat large saucepot over medium-high heat. Add sausage; cook 5 minutes or until browned, breaking up sausage with side of spoon. Add tomato & ricotta sauce, 1 teaspoon Italian seasoning, and 1/2 teaspoon each salt and pepper; heat to a simmer and simmer 10 minutes, stirring occasionally.
In large bowl, whisk garlic, eggs, ricotta cheese, Alfredo basil sauce, Parmesan cheese, sour cream, and remaining 1 teaspoon Italian seasoning, and 1/2 teaspoon each salt and pepper; transfer to saucepot with spaghetti and toss.
Spread spaghetti mixture in prepared dish; top with sausage mixture and sprinkle with mozzarella cheese. Cover dish tightly with aluminum foil; bake 30 minutes. Remove foil; bake 10 minutes or until edges are bubbly and top is lightly browned. Let stand 10 minutes; cut into 12 (3 1/4 x 3-inch) pieces.
