1. Melt butter in medium saucepan over medium heat. Add flour and 1/4 teaspoon salt and cook until flour is slightly brown, about 3-5 minutes

2. Pour in milk, whisking constantly until mixture is smooth. Stir until boiling and then reduce heat to low. Simmer until mixture thickens a little, about 10 minutes, stirring every few minutes.

3. Meanwhile, cook pasta until al dente, drain and return to pot. Remove sauce from heat, whisk in cheese and stir until cheese is melted. Add pasta and stir to coat. Serve immediately.