Rotini with two cheeses (fancy mac & cheese)

*Rotini with Two Cheeses
12 oz. rotini pasta
1 & 1/2 Tbsp. salt
1/4 c. butter
1/4 c. all p. flour
1 Tbsp. seasoned salt
2 tsp. dry mustard (I use spicy mustard)
1/4 tsp. white pepper
3 & 1/2 c. milk
1/2 lb. mushrooms, sliced
4 green onions, sliced
1 Tbsp. Worcesteshire sauce
4 oz. Swiss cheese, shredded
4 oz. cheddar cheese, shredded
1. Add rotini and salt to large pan of boiling water; cook, stirring occasionally until almost but not quite tender.6 to 7 minutes. Drain.
2. Melt butter in med. saucepan over med. heat. Stir in flour, salt, mustard and pepper until smooth; cook and stir until bubbly. Gradually whisk in milk; cook and stir until mixture thickens and bubbles for 1 minute.
3. Add mushrooms, 3 of the onions and worcestershire sauce to saucepan; mix well. Add swiss and cheddar cheeses; cook and stir over med.-low heat until cheeses are melted.
4. Combine rotini and cheese sauce in large bowl; mix well. Transfer to greased 2 qt. baking dish. Bake in preheated oven for 45 minutes (350 degrees). Garnish with remaining green onions.