In a heavy skillet, heat olive oil on medium-low and add garlic. Cook, stirring occasionally, until garlic is soft but not brown.
Add mushrooms and season with salt and pepper. Raise the heat to medium-high, stirring to incorporate the garlic and seasonings. Cook, tossing occasionally, until mushrooms render their liquid and begin to brown, about six minutes.
Raise the heat to high, add the sherry and cook, stirring, to continue browning the mushrooms and evaporate the wine.
Remove from heat, adjust seasoning and serve immediately.