In a large skillet over medium-high heat, melt the butter. Add the garlic and mushrooms and cook until the mushrooms have given up their liquid and are beginning to brown, 5 to 10 minutes.
Add the lemon juice, sherry, stock, and chile and bring to a boil. Reduce the heat to medium-low and let the mixture simmer, uncovered, for about 10 minutes, or until the liquid is quite syrupy and nearly evaporated.
Season with salt and pepper, garnish with parsley, and serve with crusty bread, if desired, for sopping up the juices.