Preheat oven to 375 degrees. Add butter a 2-quart shallow
baking dish. In a 6-quart kettle bring 5 quarts salted water
to a boil for cooking pasta. In a heavy saucepan melt butter
over moderately low heat and stir in flour and paprika. Cook
roux, whisking 3 minutes and whisk in milk and salt. Bring
sauce to a boil, whisking and simmer, whisking occasionally,
3 minutes. Remove pan from heat. Stir pasta into kettle of
boiling water and boil, stirring occasionally, until al dente.
Drain pasta in a colander and in a large bowl stir together
pasta, sauce, Worcestershire sauce and 2 cups Cheddar.
Transfer mixture to prepared dish. Macaroni and cheese may
be prepared up to this point 1 day ahead and chilled, covered
tightly. In a small bowl toss remaining 3/4 cup Cheddar with
bread crumbs and sprinkle over pasta mixture. Bake macaroni
and cheese in middle of oven 25 to 30 minutes, or until golden
and bubbling, and let stand 10 minutes before serving.