Preheat the oven to 375°F and line a baking sheet with parchment paper. Arrange the mushroom caps on the sheet with the open side up.
Heat the olive oil in a skillet over medium heat. Add the chorizo and cook for 5 to 6 minutes, breaking it into small pieces until browned.
Stir in the minced garlic and cook for 1 minute more. Remove the skillet from the heat.
Mix in half the shredded Manchego, the panko breadcrumbs, parsley, salt, and pepper until evenly combined.
Spoon the filling into each mushroom cap, pressing gently to pack it in. Sprinkle the remaining Manchego over the tops.
Bake for 15 to 18 minutes until the cheese melts and the mushrooms soften.