Preheat your oven to 350°F (175°C) and grease a baking dish to prevent sticking.
Cook the 6 cups white rice according to the package directions. Steam or microwave the frozen broccoli until tender, then drain any excess water.
In a saucepan over low heat, melt the 2 sticks butter. Add 24 ounces Velveeta and stir until the mixture is smooth and creamy.
In a large bowl, mix together the cooked rice, 32 ounces broccoli , melted cheese mixture, 21 ounces cream of mushroom soup and 1 cup milk . Stir until everything is well combined.
Pour the mixture into the prepared baking dish and spread it evenly.
Crush the 2 cups Ritz crackers and sprinkle them evenly over the casserole for a buttery, golden topping.
Place the dish in the oven and bake for 25-30 minutes, or until the casserole is bubbly and the topping is golden brown.
Let the casserole cool for a few minutes before serving. Enjoy this creamy, cheesy side dish alongside your favorite main course!