Use short pasta with ridges, such as penne rigate or rigatoni, to capture the spicy cheese sauce in the ridges and hollows of the pasta.
Cook pasta in large saucepan as directed on package for al dente pasta. Drain well.
Meanwhile, 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.
Serve with remaining 1 cup Cheddar cheese, green onions and additional Seasoning.
To bake Sriracha Cheddar Mac: Prepare as directed in steps 1 and 2. Stir green onions into pasta mixture. Spoon into 2-quart baking dish. Sprinkle with remaining 1 cup cheese. Bake in preheated 350°F oven 15 to 20 minutes or until bubbly.