Step 1

Preheat the oven to 425°F.

Step 2

Soak the mushrooms in hot water for 15 minutes. Drain and chop.

Step 3

Prepare the vol-au-vents (puff pastry case): cut out 36 discs from the puff pastry dough with a fluted round cookie cutter (2 1/2" diameter). Cut holes into the center of 18 discs with a smaller smooth cookie cutter (1 1/2" diameter) to form rings. Beat the egg yolk with a Tbsp. of water. Perforate the 18 whole discs with a fork, brush them around the edges with the egg yolk, then place the rings on top, sticking them together. Line a tray with parchment paper and place the vol-au-vents on it. Bake for 10-12 minutes. Remove from the oven and break open the center to create a hole for the filling.

Step 4

Sauté the chopped onion in 1 Tbsp. oil; trim and chop the sweetbreads, chicken hearts and livers, add to the onion along with a bay leaf. Season with salt and pepper and cook for 2 minutes. Add a splash of wine, then add the mushrooms. Cook with the lid on over low heat for an additional 6-7 minutes. Fill the vol-au-vents with meat mixture and place them back in the oven for 4-5 minutes. Garnish with fresh herbs to taste.