In 30 g of butter, brown the sliced shallots with the oyster mushrooms, cleaned and cut into pieces. Add the tomato paste, thyme, mussels and stir for 1 min.
Sprinkle with flour, add the wine. Season with salt and pepper and simmer for 3 minutes over medium heat, stirring occasionally. Stir in the cream and dill and simmer for 5 minutes until a smooth sauce is obtained. Preheat the oven to 180°C. Melt the remaining butter
Cut 6 discs of dough from 3 sheets of brick pastry. Place one disc in the middle of a sheet of brick pastry and brush with butter. Place 2 spoonfuls of mushroom moulds in the centre, set aside a few moulds for the presentation. Fold the sheet of brick pastry into a small packet, fold underneath. Coat again with melted butter. Do the same for the other 5. Place them on the baking sheet covered with greaseproof paper.
Cook for 10 minutes, watching carefully. Serve hot, decorated with a few reserved mussels and a cordon of sauce.