Gently clean the mushroom caps with a damp cloth, then carefully remove the stems and set the caps aside. Finely chop the stems to maximize flavor and moisture retention.
In a mixing bowl, combine the chopped mushroom stems with shredded cheddar, toasted breadcrumbs, minced garlic, and chopped parsley. Season with salt and pepper to taste, then mix until well blended.
Using a spoon or piping bag, generously fill each mushroom cap with the prepared mixture, pressing lightly to pack the filling in.
Arrange the stuffed mushrooms on a baking sheet lined with parchment paper. Brush the mushroom caps lightly with olive oil for extra crispness and added flavor.
Preheat your oven to 190°C (375°F). Bake the mushrooms for about 20 minutes, or until the tops are golden brown and bubbling, and the mushroom caps are tender.
Once baked, remove the mushrooms from the oven and let them rest for 5 minutes. This helps the filling set and makes them easier to serve.
Garnish with extra chopped parsley or a drizzle of balsamic vinegar if desired, then serve warm and enjoy the savory, cheesy explosion of flavors.