Step 1

Heat oven to 350°. In a Dutch oven or large cast iron skillet over medium heat, melt butter. Add flour, salt, pepper, and dill and continue whisking and cooking 2 minutes, until lightly browned and bubbling.

Step 2

Slowly add milk and half-and-half. Stir, whisking constantly until thickened, 8-10 minutes.

Step 3

Remove sauce from heat. Add cheese and stir until completely melted. Add remaining pasta ingredients and stir again.

Step 4

Make the topping by pulsing croutons and Parmesan in a food processor until finely ground. Add in melted butter and pulse again, briefly. Sprinkle over pasta.

Step 5

Bake casserole for 30 minutes. Cool 10 minutes before serving.