Preheat the oven to 425 degrees F. Lay the mushroom caps out on a baking sheet and set aside.
In a mixing bowl stir together the cream cheese, artichoke hearts, spinach, garlic, salt and pepper.
In a second bowl stir the panko breadcrumbs and Parmesan cheese together. Drizzle in the olive oil and toss to coat.
Fill each of the mushroom caps with 1-2 tablespoons of the cream cheese mixture.
Gently dip the top of each mushroom into the breadcrumbs and then return to the baking sheet.
Bake the mushrooms until the cheese is melty and the breadcrumbs are nice and golden brown, about 20 minutes.
