24 large button mushrooms (big ones), stems removed and finely chopped
100 g parmigiano reggiano, ground in a food processor
255 g cup plain panko
113 g cup mayonnaise
85 g cup finely chopped fresh flat-leaf parsley
freshly ground black pepper
1-1/2 tbs extra-virgin olive oil
Position a rack in the center of the oven and heat the oven to 220°C.
Melt the butter in a pan over medium heat. Set aside 2 tbs of the melted butter in a small bowl. Add the mushroom stems and 1/4 tsp. salt and cook about 5 minutes.
Meanwhile, add 2 tbs of the parmigianino and the panko to the reserved melted butter and mix.
In a medium bowl, stir together the remaining parmigianino, the mayonnaise, parsley, and 1/4 tsp black pepper. Add the mushroom stems and mix until well combined.
In a large bowl, toss the mushroom caps with the oil. Fill each mushroom cap with a good teaspoon of the filling and top each with about 1 tsp of the panko mixture. Place on a
large baking sheet. Bake for 25 minutes untill the topping is golden-brown.