Instructions

1. Preheat the oven to 180°C (350°F).
2. Place the mushrooms on a baking tray and drizzle over the olive oil. Bake the mushrooms for 15-20 minutes or until they are golden.
3. Place the mushrooms into a food processor and blitz until they are finely chopped.
4. Add the sea salt, black pepper, porcini powder, Dijon mustard, crème fraîche and egg yolks. Blitz again until you have a smooth mixture.
5. Cut out circles from the puff pastry sheets to fit the holes in a mini muffin tin or mini tart tin. If you are not using non-stick tins, make sure you lightly grease the tins first.
6. Spoon the mushroom mixture into the pastry cases.
7. Bake the tarts for 15-20 minutes or until the pastry is lightly golden.
8. Remove the tarts from the tin and garnish with fresh marjoram or oregano leaves, or even some finely chopped chives.
9. These tarts taste best straight from the oven, but they are also good at room temperature, which is good to know if you wish to make them a bit ahead of time.