| Preheat oven to 350°F |
| Grease an 8x8-in or 2-qt baking dish |
| 8 oz elbow macaroni | boil in salted water 7 min, just tender, drain | stir together, spread in dish | sprinkle over | bake 350°F 25 to 30 min, until bubbly and golden |
| 3 Tbsp butter | melt, whisk in, cook 1 min | whisk in, simmer until thickened, about 5 min | stir in off heat until melted |
| 3 Tbsp all-purpose flour |
| 2 1/2 cups whole milk |
| 3/4 tsp salt |
| 1/4 tsp black pepper |
| 1/2 tsp dry mustard |
| 3 cups sharp cheddar cheese, shredded |
| 2 Tbsp butter, melted | toss together |
| 1/2 cup dry bread crumbs |