• Unsalted butter, for the parchment
• 8 uniform-size brown or white mushrooms, about 9 oz (250 g) total
• ¼ lb (115 g) ground pork or veal
• 3 tablespoons dried bread crumbs, plus more for topping
• 1 egg yolk
• 2 tablespoons chopped fresh flat-leaf parsley, plus whole leaves for garnish
• Salt and black pepper
• Olive oil, for drizzling

Preheat the oven to 400°F 200°C). Line a sheet pan with parchment paper and butter the paper.

Remove the stem from each mushroom to create space for the stuffing, then brush the mushrooms clean. Place the mushrooms, hollow side up, on the prepared pan.

To make the stuffing, in a bowl, mix together the pork, bread crumbs, egg yolk, and parsley and season with salt and pepper. Divide the stuffing into 8 equal portions, shape each portion into a ball, and then place a ball in the hollow of each mushroom. Drizzle a little oil over each mushroom and sprinkle lightly with bread crumbs.

Bake the mushrooms until the stuffing is cooked through and the mushrooms are tender when pierced with a knife tip, about 20 minutes. Garnish each mushroom with a parsley leaf and serve warm.