Remove stems from mushrooms. Chop stems, then set aside for later.
Brush mushroom caps with olive oil, then bake (gill-side down) for 15 minutes, or until tender.
Flip mushroom caps over (gill-side up), then season with salt and pepper. Set aside.
While caps bake, heat butter in a medium frying pan over medium heat. Add mushroom stems and shallot. Season lightly with salt and pepper, then cook until browned (stirring frequently).
Add garlic and cook just until fragrant, about 30 seconds.
Remove frying pan from heat, then stir in stuffing, parmesan, and green onion. Season with salt and pepper (if needed).
Mound stuffing onto mushroom caps, then bake until hot and stuffing is lightly browned (about 10 to 15 minutes).
Serve hot. Enjoy!
If your stuffing is chunky, finely chop it before measuring. Smaller pieces work best for this recipe.Don't have leftover stuffing? You can use a store bought mix instead (prepare as directed).The stuffing mixture (step 7) should hold together loosely when compressed. If it seems dry, add a tablespoon (or two) of broth.Check out info before this recipe for more tips and tricks!