⅓cuppanko crumbs,(gluten-free, if necessary)
Heat oven to 375°F. Remove stems from mushrooms and finely chop them. Wipe mushroom caps carefully with a damp soft cloth or paper towel.
Toss mushroom caps with 2 tbsp olive oil and salt and pepper on a baking sheet. Place stem side down and bake for 25 - 30 minutes or until tender.
Meanwhile, heat remaining 2 tbsp oil in a medium skillet and add garlic. Cook until golden, 4 - 6 minutes. Transfer to a paper towel to drain. Add chopped mushroom stems, shallot, salt and pepper, cook until shallot is soft.
Add sherry or wine and cook until it evaporates. Remove to a small bowl and stir in parsley, sage, garlic, blue cheese, panko crumbs and finally, the egg white. Stir until well combined.
Fill mushroom caps with 2 tsp of the filling. Return to baking sheet and broil until tops are browned, 3- 4 minutes. Serve hot.
If you don't have sherry, you could use another fortified wine like madeira or even a dry white wine or apple cider. These substitutions won't provide the same depth of flavour, but since I only used 3 tablespoons in this recipe, it won't change it too much.