Heat the oil in a small frying pan over a medium heat. Sprinkle the bread with the chopped and then fry on both sides for 1-2 minutes.
Remove the fried bread from the pan and keep warm. Add the onion, extra oil and mushrooms to the pan and fry over a high heat for three minutes.
Stir through the mustard, white wine and double cream and season with sea salt and freshly ground black pepper. Leave to simmer on a low heat until the mixture thickens.
To serve, place the fried bread onto a serving plate and spoon over the creamy mushroom mixture.