Place the puff pastry slices next to each other and defrost. Clean, clean and slice the mushrooms. Dice bacon. Peel and finely dice onion. Wash thyme, shake dry and pluck off leaves, except for something to garnish.
Heat the oil in a frying pan. Leave the bacon in it and take it out. Fry the mushrooms for about 5 minutes, turning them over, add onion, bacon and thyme, season with salt and pepper. Beat the eggs and milk, season with salt, pepper and nutmeg.
Roll out puff pastry slices (each 14 x 14 cm). Cold rinse 4 moulds (each 11 cm Ø), place 1 puff pastry slice in each and press the edge firmly. Spread the mushroom mixture in it and pour egg milk over it.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-30 minutes. Remove and garnish with remaining puff pastry.