1Cook pasta in large saucepan as directed on package for al dente pasta. Drain well.
2Meanwhile, melt butter in medium saucepan on medium heat. Sprinkle with flour and Seasoning. Cook and stir 1 minute or until well blended. Gradually stir in milk until smooth. Stirring constantly, cook 2 minutes or until sauce starts to thicken. Stir in 1 cup of the Cheddar cheese and Gruyere cheese until melted and smooth. Remove from heat. Add pasta; toss gently to coat.
3Serve with remaining 1 cup Cheddar cheese, green onions and additional Seasoning.