Cheesy Chicken, Broccoli & Rice Casserole (From Scratch!)

Preheat oven to 400 degrees F. Butter a 9x13-inch casserole dish.

Melt 2 tablespoons of the butter over medium heat and add the sliced mushrooms. Saute, stirring occasionally, until the mushrooms are cooked down and all of the liquid has evaporated. Transfer the mushrooms to a separate bowl.

In the same pan, melt the remaining 4 tablespoons of butter over medium heat. Once the butter has melted, whisk in the flour and cook for about 1 minute, until the flour starts to brown a bit and smells nutty, whisking constantly. In a slow, steady stream, whisk in the milk. Allow the sauce to come to a simmer.

Once the sauce comes to a simmer, whisk in the cheddar cheese, adding a handful at a time and whisking until completely melted before adding the next handful. Season with salt and pepper and turn off the heat.

Add the chicken, broccoli, rice, and cooked mushrooms to the sauce. Stir with a wooden spoon until everything is completely combined and evenly distributed. Pour the mixture into the prepared casserole dish.

In a small bowl, mix the melted butter with the breadcrumbs (or Ritz crackers).

Sprinkle the casserole with the ½ cup of shredded cheese. Sprinkle the breadcrumb mixture on top of the cheese.

Bake until browned and bubbly, about 15 to 20 minutes. Allow to sit for 10 to 15 minutes before serving.