Add half of the mushrooms to a food processor and pulse until you end up with a small, crumble like texture (see step-by-step photos). Chop the other half into small pieces.
Heat 2 tablespoon of olive oil in a large skillet over medium heat.
Add spring onion and garlic and cook until onion is soft. Stir once or twice to avoid burning.
2 green onions, 3 garlic cloves
Add both minced and chopped mushrooms. Season with a pinch of salt and soy sauce and let simmer over medium-low heat until all of the water has evaporated from the mushrooms (~10 minutes).
2 tablespoon soy sauce
Season with thyme, majaram and rosemary. Let simmer for 2 more minutes.
1 teaspoon thyme, 1 teaspoon majoram, 1 teaspoon rosmary
Add cooked butternut squash cubes, crumbled feta, crumbled chestnuts and pine nuts to the cooked mushroom mixture. Mash together all of the ingredients by stirring vigorously so that a sticky mass forms.
¾ cup coarsley crumbled feta, 1 cup cooked chestnuts
Spoon the mushroom filling into the center of piece of parchment paper. Roll the filling inside the paper like a sausage and twist the ends of the parchment paper to compress the filling and create a sausage shape (see step-by-step photos or video). Roll out a puff pastry and place the filling into the center of the pastry. Leave some space on every side.
Fold the sides of the pastry, running along the length, over. The pastry should overlap in the middle. Trim the ends of the pastry.
Make up an egg wash by whisking together an egg and 1 tablespoon of water in a small bowl. Use a pastry brush to lightly brush the egg wash over the pastry. Bake it in the oven for 30-35 minutes or until it’s golden brown. 1 egg