Spinach and Boursin Stuffed Mushrooms

medium-large white button mushrooms (cleaned and stemmed)

butter

garlic (minced)

frozen spinach (thawed and squeezed)

kosher salt

freshly ground black pepper

block of Boursin ((Garlic & Herb or Shallot & Chive))

plain panko crumbs plus extra for sprinkling

grated parmesan cheese

olive oil for drizzling