By Gary Rhodes
Lightly butter a baking tray. Trim and discard the tip of the mushroom stalks and place on the tray, stalk-side up. Season with salt and pepper. Using half the butter, put small knobs on each of the mushrooms.
Melt the remaining butter in a large deep frying pan and once sizzling, add the onions and fry over a medium-hot heat for 8-10 minutes until softened and lightly coloured. Season with salt and pepper.
Meanwhile, preheat the grill and cook the mushrooms for 6-8 minutes until tender. Spoon the onions on top of the mushrooms.
Mix the two c