Clean the mushrooms and slice them thinly.
Heat a wide pan over medium-high heat.
Add the sliced mushrooms to the hot pan and cook until the water evaporates.
Add a generous knob of butter to the pan and let the mushrooms brown properly, stirring occasionally, for another 5-8 minutes.
Season the mushrooms with salt and a bit of black pepper if you like. Remove from the pan and set aside.