1. Brush a griddle pan with olive oil and put over a high heat. Slice the sourdough loaf so you have 2 thick slices for each person then toast each slice on both sides on the griddle pan so you have grill marks on the bread. (If you don’t have a griddle pan, toast under the grill and brush with the olive oil.
2. Melt the butter in a large saucepan or frying pan until bubbling. Add the mushrooms with some salt and pepper and cook on a high heat. Add the garlic after a minute and fry until the mushrooms are soft and evenly browned.
3. Stir in the crème fraiche and parsley then leave to bubble for a few minutes. Add further seasoning if required.
4. Arrange the mushrooms on the slices of toast and top with the grated parmesan before serving.