This is everyone’s favorite casserole, not least because on Thanksgiving Day it’s the only rice dish on the table (and my Korean family loves rice). When my cousin Becky finally learned how to make broccoli-cheese rice casserole from her Aunt Anne, whose Southern food I always thought tasted so good, she usually made two vats of it because it’s the one dish everyone wants leftovers of. (It also happens to reheat especially well—a key requirement for any Thanksgiving side dish, in my book.) What I love most is how much this recipe has changed over time. I call it Aunt Anne’s Broccoli-Cheese Rice Casserole because she’s the catalyst for the dish, but really it’s “Eric’s interpretation of Becky’s Broccoli-Cheese Rice Casserole, which she maybe learned from her mother, Julia, who learned it from her sister Anne.” Like a game of telephone, the recipe has been tweaked and misremembered, and now tastes like a mere version of that first casserole we had as kids, which is fine because we’re not kids anymore. And I love that. This kind of culinary evolution is what defines Thanksgiving for me. As for the broccoli, sometimes I like to use only florets because that’s my favorite part of the vegetable, but my mother likes it the way Aunt Anne makes it, which was often with frozen chopped broccoli (stems and everything). The original had Velveeta cheese, as well, but I enjoy the sharpness of cheddar and the ease of ready shredded cheese, which is what I call for here.
Preheat the oven to 350 degrees F. Grease a 9 × 13-inch baking dish with softened butter.
In a large skillet, melt the 1 stick of butter over medium high heat. Add the onion, sprinkle with the sugar, and season with salt and pepper. Reduce the heat to medium-low and cook, stirring occasionally, until the onion is slightly caramelized, 15 to 20 minutes.
Add the bread to the buttery onions, increase the heat to medium, and sauté until slightly toasted, 10 to 12 minutes. Remove from the heat.
In your biggest bowl, use your hands to toss together the rice, frozen broccoli, cheddar, sour cream, milk, 2 teaspoons salt, and the buttery onion-bread mixture until well mixed. Spread evenly into the greased baking dish. (You can make this ahead up to this point; see Cook’s Note.)
Bake the casserole until bubbling, warmed through, and slightly browned at the edges, 30 to 40 minutes. Serve warm. Refrigerate leftovers in an airtight container for up to 4 days.
You can prep this casserole completely in advance (just don’t bake it yet) and freeze it for up to 1 month or refrigerate it for up to 3 days. Just add a few minutes to the bake time when you’re ready to cook it.