Heat the oil over a medium heat and add the mushrooms, stirring occasionally while they soften for about 3 minutes.
Crush the garlic and add to the pan for a minute and season with the pepper.
Cook for a few more minutes until the liquid has been absorbed. Leave to cool.
Line a large baking sheet with greaseproof paper and cut 4 squares about 14cm or 6 inch square.
Score a line about 1cm in from the outside edge, without going all the way through.
Spread the crème fraîche equally in the middle of each square and top with the mushrooms.
Make an egg wash with the beaten egg and water and brush the pastry edges.
Bake in the oven for 20 minutes until the borders are well risen and golden.
💭 Top tip
There's no need to wash mushrooms if they have soil on them. Wipe them with damp kitchen paper. They are like little sponges, so if they have been immersed in water they will release the water as they cook and dilute the flavour of the oil.
Disclaimer:The nutritional information provided is approximate and is calculated using online tools. Information can vary depending on various factors, but we have endeavoured to be as accurate as possible.