Trim fresh broccoli, and cut into small 1 inch pieces. Place in a steamer and steam for 5 to 7 minutes, or until broccoli is bright green.
In a medium saucepan, melt butter, and add chopped onion, cook until transparent. Add the cheese, soup, broccoli, and rice to the onions and stir through to melt the cheese and heat it all.
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 it in a 350 degree F oven for about 20 minutes, until hot and bubbly.