Spray a 2 litre (3½ pint) casserole lightly with spray oil. Put the rice in the prepared dish and pour over the stock. Add a little salt and pepper, stir once and cover with a tight-fitting lid (add a layer of foil if necessary).
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 40 minutes until the rice is tender and most of the stock has been absorbed.
Meanwhile, melt the butter in a small saucepan and cook gently for 2–3 minutes until the butter browns to a nutty colour.
Remove the risotto from the oven and stir in the Parmesan and the browned butter. Serve immediately.