1 large lemon, zested and squeezed to yield around 2 tablespoons juice
1/4 cup rosemary leaves
3 medium cloves garlic
1 tablespoon olive oil
1 tablespoon unsalted butter
1 lb. mushrooms, such as baby portabellas or white button, cleaned with large ones cut in half
salt and pepper to taste
Preheat the oven to 375°F.
Combine the rosemary, lemon zest, and 1 garlic clove and chop to combine. Add a pinch of salt and mix well.
Heat the oil and butter in a 12-inch skillet over medium-high heat. Cook the mushrooms with 2 garlic cloves smashed with the side of a chef’s knife. Season to taste with salt and pepper and cook, stirring occasionally, until the mushrooms soften, about 5 minutes. Pour in lemon juice and let it reduce by half, another 5 minutes.
Take a large piece of parchment (or buy premade parchment bags from the grocery) and place the mushroom mixture in the center. Sprinkle the rosemary, lemon, garlic mixture over the mushrooms. Fold the parchment over the mushrooms and crimp and pleat the edges to seal tightly, starting at one corner of the fold and working your way to the other end, making sure the seals are tight. You can do this up to 2 hours ahead.
Put the packet on a baking sheet and bake until the mushrooms are warmed through, about 10-15 minutes. Slice open the packet and serve family style.