Peel and chop the onion. Melt the butter in a large casserole dish over a medium heat, add 2 tablespoons of the olive oil and tip in the onion. Stir and sizzle for 2 minutes.

Roughly slice the mushrooms and add to the dish. Cook for 5 more minutes, until the mushrooms have reduced in size. Add the rice and stir well.

Pour in the Madeira, stir and allow to reduce down. Begin adding the stock, a little at a time, stirring until the rice has absorbed the stock before adding more. Continue until all of the stock has been used and the rice is plump and tender.

Stir in the thyme, then turn off the heat. Add the remaining olive oil and the parmesan to the risotto (don’t stir it) and put the lid on the dish. Leave for 5 minutes, then stir well and serve.