Place the broccoli into a steamer and steam for 5 to 7 minutes, until it turns bright green.
In a medium saucepan, melt the butter. Add the chopped onion and sauté until the onion becomes translucent.
Add the cheese, cream of chicken soup, broccoli, and rice and stir until the cheese is melted and the mixture is heated through.
You can serve this dish now, or you can put it in an 8-inch square baking pan, cover, and refrigerate. When you are ready to serve, uncover and reheat in a 350°F oven for about 20 minutes, until hot and bubbly.
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Recipe Tips
Dice the cheese rather than dropping it in as a block. Small cubes melt evenly at low heat, and low heat is what keeps the sauce from turning grainy.
Fold, do not stir vigorously, once the rice goes in. Aggressive stirring shears the broccoli into confetti and knocks the starch out of the rice.
The casserole thickens as it cools and firms up considerably in the refrigerator. That is normal. A splash of milk stirred in during reheating brings the texture right back.
If you want browning on top, run the finished casserole under the broiler for 2 to 3 minutes at the end. Watch it closely, since the cheese sauce goes from gold to scorched quickly.
Taste before you add salt. Between the processed cheese and the canned soup, the dish arrives well seasoned on its own.