Preheat the oven to 400°F/200°C/Gas 6. Line a rimmed baking sheet with a piece of parchment paper. Brush the mushrooms with olive oil and place them on the prepared baking sheet.
Place the cream cheese, Parmesan, 3 tablespoons of breadcrumbs, scallions, and parsley into a medium mixing bowl. Season to taste with salt and pepper and mix well.
Fill each mushroom cap with the cream cheese mixture. Sprinkle the remaining breadcrumbs on top.
Bake the stuffed mushrooms in the preheated oven for 20-25 minutes or until the mushrooms are tender and the breadcrumbs are golden brown. Remove from the oven and leave to rest for 10-15 minutes before serving. Enjoy!