Preheat the oven to 180c [ 350F ] Gather and weigh your ingredients
Cut the mushrooms into large, bite sized pieces and place in a bowl with the garlic, ginger, shallots, thyme, salt and pepper and toss to mix well
Cut the parchment into 30cm [12 inches] squares. Divide the mushroom mixture between the four squares and drizzle with the olive oil and dot each with 10g of butter.
Pull the parchment up and fold over and seal the edges
Place on a baking sheet and cook on the middle rack of the oven for 15-20 minutes. The parcels should have puffed up a bit and the mushrooms will be tender
Meanwhile, mix the fresh parsley and tarragon in the mascarpone and incorporate well.
Place one parcel on each plate and open the top. Add a dollop of the mascarpone mixture and serve immediately