Heat the oven to 375 degrees and line a baking sheet with parchment paper.
Wipe the mushrooms clean with a damp cloth. Twist off the stems and set the caps aside. Finely chop the stems.
Warm 1 tablespoon of olive oil in a skillet over medium heat. Add the onion, garlic, and chopped mushroom stems. Cook for 4 to 5 minutes until the onion softens.
Transfer the cooked mixture to a mixing bowl. Stir in the cream cheese, cheddar cheese, salt, and pepper until evenly combined.
Brush the outside of each mushroom cap with the remaining tablespoon of olive oil. Spoon the cheese filling into the caps, mounding it slightly.
Sprinkle panko breadcrumbs over the filled caps. Place them on the baking sheet and bake for 18 to 20 minutes until the tops turn golden.
Remove from the oven and let cool for 3 minutes. Press two olive slices onto each cap to form eyes.