Preheat oven to 400˚F.
On the work surface, place an 18-24-inch sheet of parchment paper lengthwise.
Using the lower half of the parchment paper, place the mushrooms down in a circle .
340 grams mushroom
Sprinkle with salt, pepper, and herbs. Distribute the butter pieces evenly around the mushrooms. Drizzle the balsamic vinegar over the mushrooms.
⅛ tsp salt, ⅛ tsp pepper, 2 tsp butter, 1 tsp thyme, 1 tsp rosemary, 1 tsp balsamic vinegar, 1 tbsp parsley
Fold the upper half of the parchment paper over the mushrooms (you should leave enough space around the food to allow the air to expand and circulate). Starting from the upper right corner, make a fold in the parchment, continue folding along the half moon with overlapping folds. You should be making very tight, closely overlapping little folds starting from one corner and work your way around, towards the opposite corner. Fold the last fold over itself, staple the last fold to itself, and then staple a few of the folds along the parchment paper.
Place the package on a baking tray and bake for 20-30
Cut the package open and either slide the contents onto a plate or serve directly from the open parchment (you can cut away the top flap and staples).