Prepare the quinoa:
Place the quinoa in a small saucepan with the water and bring to the boil. Reduce the heat, cover and simmer for 10 minutes until all the water is absorbed and the quinoa is cooked. Cool a little.
Prepare the mushrooms:
Gently wipe over the mushrooms and remove the stalk. Put 8 of the mushrooms aside and finely chop the remaining mushrooms including all of the stalks if they are not too woody or tough.
Prepare the condiments:
Preheat oven to 190ºC and line a baking tray with baking paper. Heat oil in a non-stick frying pan and sauté the scallions until lightly browned. Add the chopped mushrooms and cook for 3-4 minutes until the mushrooms collapse. Stir in garlic and parsley, cook for 1 minute, remove from the heat and cool. When cooled, stir in the quinoa, roasted capsicums, mozzarella and parmesan cheeses, and season.
Place mushrooms top side down onto the tray, cover the underside of each mushroom with some to filling squashing it down tightly as you fill it. Drizzle olive oil and sprinkle with extra parmesan cheese. Bake for about 15 minutes until the cheeses have melted. To make the dressing, mix all the ingredients together. Drizzle the mushrooms with some of the dressing before serving.