1. Wash and slice the mushrooms while removing the stems.
2. In a pan, heat about 2 oz of butter and cook the mushrooms slowly until it turns soft. Season well with salt and pepper.
3. Cool at room temperature and chill the mushrooms.
4. Beat the remaining butter with chives, parsley and garlic. If required, season with salt and pepper.
5. Pour the mixture in the mushroom caps and serve chilled as a side dish for grilled steak or chops.