1. Heat a small saucepan over low-medium heat and add the butter and onion. Fry the onions, stirring occasionally, for about 40 minutes until caramelised and golden. 

2. Heat your oven to 200C fan-forced (220C conventional). Place the onions in the base of a gratin dish. Separate large florets from the broccoli and peel the stems. Cut the stems into pieces around the same size as the florets. Arrange the stems and florets on top of the onion. Mix the cream and cheese together and pour over the broccoli. Bake for 30 minutes until the broccoli is tender, then grill until the top is bubbling and golden. 

Adam's tip: I caramelise onions by putting them in a pot over low heat and setting a timer for 6 minutes. When the timer goes off, I give the onions a stir and then set the timer again, repeating for about 40 minutes until the onions are perfectly caramelised.