The night before, measure 1 cup of quinoa and place in a bowl of 1-2 cups of water, cover to soak.
After quinoa has soaked overnight, stir and drain through a fine mesh strainer. Rinse and repeat at least two more times until the water is clear.
Boil 2 cups of chicken broth and add the soaked quinoa. Return to a boil, cover and reduce to medium heat. Simmer about 12-15 minutes until broth is absorbed. Fluff and let stand for 15 minutes.
Preheat oven to 350℉
Meanwhile chop mushroom, scallions, and garlic. Add a little water to a pan, and follow the instructions for cooking sausage on the package. Crumble up the sausage with a spatula while it sautés, about 15 minutes. Stir in the chopped mushroom and continue to sauté with the sausage, about 3 minutes. Add the garlic, green onions and cooked quinoa. Continue to sauté for about 3 minutes. Add the marscarpone cheese and stir well, continuing to sauté, until creamy and melted into the stuffing. Remove from heat and allow to cool slightly. Add parmesan and stir. Sprinkle with salt and pepper.
Place peppers in a slightly oiled baking dish and stuff equally, gently packing down the stuffing.