How to Make It
Melt butter in a large saucepan over medium heat. Whisk in flour, and cook 2 minutes, stirring constantly. Whisk in milk, bring to a simmer, and cook 6 to 8 minutes or until slightly thickened, stirring occasionally. Whisk in tomato paste, and cook 1 minute. Remove pan from heat, and stir in cheese, salt, and pepper.