"Upgrade the classic app just in time for party season...."
butter
finely chopped onion
button mushrooms, stemmed and chopped
cloves garlic, minced
finely chopped parsley, plus more for garnish
block Boursin
breadcrumbs, plus more for sprinkling
grated Parmesan
kosher salt
Freshly ground black pepper
Extra-virgin olive oil, for drizzling