There's always that one person who wants to switch similar-looking ingredients in a recipe, but when it comes to mushrooms, substituting portobello for shiitake or vice versa can start to feel like a ...

Preheat the oven to 200C/180C Fan/Gas 6. Put the portobello mushrooms on a baking tray. Divide the unsalted butter between each mushroom. Season with salt and pepper and put a sprig of fresh thyme ...