Place a medium skillet over medium-high heat to preheat. Add a couple of tablespoons of olive oil to the pan and heat the oil. Add the mushrooms to the pan in a single layer. Season with salt and pepper. (Hot oil and a hot pan are important here, so the mushrooms will get nice and browned.) Let cook for about 5 minutes without stirring.
Stir the mushrooms around (they should be starting to get nice and golden by now) and reduce the heat to medium. (At this point, you can throw a teaspoon or so of butter into the pan as well, if you like a buttery flavor!) Continue cooking, stirring occasionally, for an addition 5-7 minutes or until they're as browned as you like them! (I like mine cooked for a long time until they're almost crispy.) Add a little more oil to the pan if they're not browning as much as you'd like.