6 oz. extra-sharp cheddar cheese, grated
3 cups chopped broccoli florets
Kosher salt and freshly ground black pepper
1 tsp. Dijon mustard
1 cup half and half
1 1/3 cups whole milk
2 tbsp. all-purpose flour
1 shallot, minced
2 cloves garlic, minced
2 tbsp. unsalted butter
8 oz. medium pasta shells