Pastry with Goose
Preheat the oven to 200°C (approximately 400°F). Defrost puff pastry. Cut duck meat into small pieces. Peel onion and chop. Trim mushrooms and cut into slices. Rinse leeks thoroughly and cut into thin rings. Heat goose fat in a saucepan and sauté onion with leek until onion is translucent. Add mushrooms, sauté briefly and season with salt, pepper, paprika and thyme. Allow to cool.
Mix egg with crème fraîche, meat with vegetables. Roll out 2/3 of puff pastry on a floured work surface into a size slightly larger than the tart pan. Line tart pan with parchment paper and line with puff pastry forming an edge. Spread meat filling on top of dough. Roll out remaining dough in the size of the tart pan and place it over the filling.
Press edges of the dough, cut a small hole in the center of top puff pastry, whisk together egg yolks and brush dough with it. Bake in the preheated oven until golden brown, about 35-40 minutes. Remove from oven, remove from the pan. To serve, cut into pieces and garnish with fresh thyme.