Preheat oven to 350F.
Cook pasta in large pot. Drain, saving about one cup of the water. Set pasta aside to cool. In same pot on low heat, melt
butter. Add flour. Stir for a few minutes, until mixture is lightly browned. Add milk. Cook, stirring occasionally,
until sauce bubbles and thickens, adding more flour if needed. Add cheeses. Stir until blended. Remove from heat. Add pasta,
tomatoes, and parsley. If mixture is too thick, add some of the reserved pasta-cooking water. Grease baking pan.
Bake for about 25 minutes or until lightly browned on top.