Heat oven to 350°F. Spray 2-quart casserole with nonstick cooking spray. Cook rotini as directed on package. Drain.
Meanwhile, melt margarine in large saucepan over medium heat. Add garlic; cook and stir 30 to 60 seconds. Stir in flour and pepper; cook and stir until mixture is bubbly. Gradually add milk, stirring constantly, until mixture boils and thickens. Remove from heat. Reserve 1 tablespoon each American and mozzarella cheese for top. Add remaining cheeses to sauce; stir until melted.
Add cooked rotini to cheese sauce; stir gently to coat. Pour into sprayed casserole. Sprinkle with reserved cheeses.
Bake at 350°F. for 20 to 25 minutes or until bubbly around edges.