Place a large frying pan over a high heat and add 2 tsp of olive oil. When the pan has come to heat add half the mushrooms. Leave for 1 - 2 minutes before stirring. The mushrooms should be lightly golden. Cook for a further minute before removing from the pan and repeating with the second batch. Reduce the heat to medium low and return the mushrooms to the pan and add the garlic and chili flakes and cook for 2 minutes, or until the garlic is fragrant, but not browned as it will taste bitter. Set aside to cool.