Rasp the garlic with a Microplane into a small bowl. Add the lemon juice together and mix.
Clean the mushrooms with a damp paper towel or brush to get rid of any dirt. Cut the mushrooms into quarters.
Before you begin have all of your ingredients ready to go as shown. Slice the parsley thinly and reserve in a bowl.
Put a big, heavy-bottomed sauté pan on medium-high heat. Add ¾ of the butter to the pan and get it hot and foamy.
Once the butter is just about to turn brown, add your mushrooms. Turn them so they are all lying on a cut side and don't toss the pan just yet.Continue cooking the mushrooms over medium-high heat.*If cooking in batches, reserve the cooked mushrooms in a bowl and continue cooking more mushrooms in more butter.* Add them all together and get them hot again before continuing to the next stage.
Once the mushrooms are browned nicely, add the rest of the butter and turn off the heat. Immediately add the garlic-lemon mixture and toss well. Season with salt to your liking.
Serve on a plate and enjoy alongside a main course.