Hazırlanışı
1Sauté mushrooms 5 minutes. Place puff pastry on baking paper, fold a 1 cm / 0.4" border, brush edges with butter, top with Gruyère and mushrooms. Bake on the preheated tray for 30 minutes. Finish with fresh thyme, salt flakes and truffle oil.
2Hot tray - Place a baking tray in the oven. Turn the oven on and preheat to 210°C / 410°F (190°C fan).
3Cook the mushrooms - Heat the olive oil and butter in a frying pan over medium-high heat. Add mushrooms, salt and pepper. Cook for 5 minutes, stirring regularly, until soft. Transfer mushrooms to a colander over a bowl to drain in case of excess liquid.