Preheat the oven to 375 degrees and line a baking sheet with parchment paper.
In a mixing bowl, combine the cream cheese, chopped black olives, Parmesan cheese, minced garlic, dried basil, salt, and pepper until evenly mixed.
Brush the mushroom caps lightly with olive oil on the outside.
Spoon or pipe the cream cheese mixture into each mushroom cap, filling them to the top.
Press one green olive half, cut side down, into the center of the filling on each mushroom to create the eyeball look.
Arrange the filled mushrooms on the baking sheet and bake for 18 to 20 minutes until the mushrooms soften and the filling warms through.
Remove from the oven and let them cool for a few minutes before serving.