Preheat oven or toaster oven to 400°F.

Line a baking sheet with aluminum foil and coat with a small amount of olive oil. Set aside.

Heat a large skillet or griddle (cast iron, if you’ve got it!) over medium-high heat. Add just enough olive oil to lubricate the surface. Place mushroom caps bottoms down on cooking surface. They’ll lose a lot of water as they cook, and that’s what you want. Leave for about five minutes and then flip the caps.

When you can see moisture collecting inside the cap, flip it again, pressing with a spatula to flatten.

Cook for approximately 15-20 minutes. Time can vary depending on the size of the caps, you want the caps to be about 2/3 their original size and to have released quite a bit of moisture.

Remove the caps to the prepared baking sheet, bottoms up. Add sauce, cheese and toppings. Bake for 15-20 minutes or until cheese is melted and slightly toasted.