📋 Instructions

1. 1Heat the oven and pan — Preheat the oven to 375F (190C) and butter a 9x13-inch baking dish. A glass or ceramic dish works well here because it holds heat evenly.
2. 2Blanch the broccoli — Bring a pot of salted water to a boil and drop in the florets for 2 minutes, until they turn bright green and just start to soften. Drain and rinse under cold water so they stop cooking.
3. 3Build the cheese sauce — Melt 3 tablespoons of butter in a large saucepan over medium heat, whisk in the flour, and cook for 1 minute until it smells nutty. Pour in the warm milk in a steady stream, whisking constantly, and simmer for 3 to 4 minutes until the sauce thickens enough to coat a spoon.
4. 4Melt in the cheese — Take the pan off the heat and stir in 2 cups of the cheddar, the garlic powder, onion powder, pepper, and 1/2 teaspoon salt. Stir until the cheese melts into a glossy, smooth sauce, then taste and adjust the salt.
5. 5Fold everything together — Stir the cooled rice, chicken, and broccoli into the sauce until every grain is coated. Scrape it all into the prepared baking dish and smooth the top with a spatula.
6. 6Add the crumb topping — Toss the panko with the 2 tablespoons of melted butter and scatter it over the casserole, then sprinkle the remaining 1/2 cup of cheddar on top. This double layer is what makes the crust so good.
7. 7Bake until bubbling — Bake at 375F (190C) for 25 to 30 minutes, until the edges are bubbling and the topping is golden brown. If the crumbs need more color, broil for 1 to 2 minutes, watching closely so they do not burn.
8. 8Rest and serve — Let the casserole rest for 5 minutes so the sauce sets, then scoop and serve. It should be hot all the way through and creamy at the center.