Chicken Noodle Soup Casserole

Arrange a rack in center of oven; preheat to 400°. In a large pot of boiling salted water, cook egg noodles, stirring occasionally, until al dente according to package directions. Drain, then return to pot.

Meanwhile, in a large (at least 12”) ovenproof skillet over medium-high heat, melt butter. Add onion and celery; season with a large pinch of salt and pepper. Cook, stirring, until vegetables are tender, about 7 minutes. Add garlic and flour and cook, stirring, until fragrant, about 1 minute more.

Add broth and milk. Bring to a simmer, stirring frequently, until thick enough to coat the back of a spoon, about 12 minutes. Remove from heat.

Stir in mustard, dill, and 1 cup cheese; season with ¾ tsp. salt and a few grinds of pepper. Add noodles, chicken, and peas and carrots, then stir until coated.

In a medium bowl, stir crackers, oil, and remaining 1 cup cheddar. Sprinkle over chicken mixture in skillet.

Transfer to oven and bake casserole until bubbling and cracker crumbs are browned, 20 to 25 minutes. Transfer to a wire rack and let cool slightly. Top with dill.