Preheat the oven to 400oF/205oC
Remove the stems from the mushrooms. Set aside for use in a different dish
Place mushrooms in a large bowl and toss with half of the olive oil and salt and pepper until everything is evenly coated.
Heat remaining olive oil a small skillet over medium high heat
When oil begins to shimmer, add chopped garlic and saute until just fragrant, about 2 minutes. Stir occasionally to prevent garlic from browning
Add bread crumbs and stir to combine fully with garlic. Allow to toast for a minute or two. Add kosher salt and fresh ground black pepper to taste.
Remove from heat and add chopped parsley. Stir to fully incorporate into breadcrumb and garlic mixture
Arrange mushrooms evenly on a lined baking sheet. If using foil as a liner, give a quick spray with cooking spray
Place about 1 teaspoon of mixture into each mushroom. After filling all mushrooms, divide remaining mixture among mushrooms, creating a small mound atop each mushroom
Place mushrooms in oven for about 15 minutes, until mushrooms are softened and stuffing is golden browned.
Remove from oven and let cool for 2 - 3 minutes, them arrange on a serving platter