Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch ceramic or glass baking dish with butter.

Steam chopped broccoli florets in a microwave-safe bowl with 2 tablespoons water for 3 minutes (or steam on stovetop) until vibrant bright green and crisp-tender. Drain completely.

In a large saucepan, melt 4 tablespoons butter over medium heat. Whisk in flour and cook for 1-2 minutes until bubbling and lightly golden to create a roux.

Gradually whisk in chicken bone broth and whole milk. Cook, whisking constantly, for 4-5 minutes until the sauce thickens and gently bubbles.

Remove from heat. Whisk in garlic powder, onion powder, dry mustard, paprika, salt, and black pepper. Stir in 2 cups of shredded sharp cheddar cheese until completely melted into a silky, luscious cheese sauce.

In a large mixing bowl, combine cooked rice, shredded chicken, and steamed broccoli. Pour the warm cheddar cheese sauce over top and gently fold with a spatula until evenly coated.

Transfer the mixture into the prepared 9x13-inch baking dish and smooth the surface. Sprinkle the remaining 1/2 cup shredded cheddar cheese on top.

In a small bowl, toss crushed Ritz crackers with 2 tablespoons melted butter. Scatter the buttery crumbs evenly over the cheese layer.

Bake uncovered at 375°F (190°C) for 20 to 25 minutes until the casserole is bubbling vigorously at the edges and the cracker crust is toasted deep golden brown.

Let rest for 5 minutes before scooping into bowls so the rich cheddar sauce settles into velvety perfection.