Preheat the oven to 425°F. Give the mushrooms a gentle rinse and twist the stems until they come out. Set the empty mushrooms aside.
Finely dice or pulse the mushroom stems. Also, finely mince the garlic and chop the scallions, both the wight and green parts.
Over medium heat, add 1 tbsp olive oil to a cast iron skillet. Add the scallions and garlic and cook for one minute.
Add the diced mushroom stems and cook for 8-10 minutes, until reduced in size and slightly browned. Stir occasionally. When ready, set aside.
In a separate bowl, add the lemon zest, juice, bread crumbs, and parmesan. Finely chop the parsley and add it as well.
Add the cooked mixture to the bowl. Mix until combined and season with salt and pepper to taste.
Drizzle the remaining olive oil over the empties mushrooms. Gently coat them with your hands or a brush and season with salt and pepper.
Lay out the mushrooms on a baking sheet, with the cavities facing up. Fill with the stuffing mixture, dividing it equally between the mushrooms.
Bake in the preheated oven for 15 minutes, until the stuffing is golden on top. Enjoy!