Preheat oven to 400°F.
Pat scallops dry, quarter them, and set aside.
Roast the poblano peppers directly over an open flame until the skins are blistered. Transfer to a sealed freezer bag and let steam.
Sauté diced onion in olive oil until soft. Add cooked rice and marinara sauce, mix well, then remove from heat.
Peel the steamed poblanos. In a baking dish, spread a layer of marinara sauce on the bottom. Lay the peppers in the dish, slice them open lengthwise, and gently spread to make space for stuffing.
Mix the quartered scallops and Parmesan into the rice mixture. Spoon the mixture into the peppers.
Bake for 14 minutes, or until hot and bubbly. Serve hot.
