Leaves from a few sprigs of flat leaf parsley, chopped, or ½ tsp thyme leaves
Squeeze of lemon juice
2 baps or baguette sections roughly the same size as the mushrooms
2 handfuls rocket or other leaves for the sandwiches
Salt & pepper
Preheat oven to 200°C/Gas 6. Smear top of mushroom cap with a little of the butter and place mushrooms cap side down on an ovenproof dish or tray.
Scatter the chopped mushroom stem, the garlic and herbs over the mushrooms and dot with remaining butter, covering the garlic and herbs as much as possible. Bake for about 20 minutes until mushrooms are cooked. Squeeze over some lemon juice and add salt and pepper.
Split the baps or baguette and spread with mustard or mayonnaise if you like. Pour any cooking juices onto the cut surface of the bread, then add the mushrooms and salad leaves. Close the sandwich and serve straight away.