Preheat the oven to 300°F (or 275°F on convection bake), and line some rimmed baking sheets with parchment paper. For this recipe, you’ll either need to use multiple trays or bake in several batches.

Cut the mushrooms in half lengthwise, and then use a mandoline slicer to cut them into ⅛-inch slices.

Arrange the slices in a single layer on the parchment-lined baking sheets. Make sure the mushrooms are super-dry, and leave some space between the slices.

Brush avocado oil or melted ghee on both sides of the mushroom slices, and season with salt and pepper to taste.

Bake for 45 minutes to an hour, or until the chips are golden brown and crispy. These chips won’t continue to crisp once they’re out of the oven, so don’t pull them out if they’re still kind of soft.