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