Preheat oven to 400°F.
In a 4 - 6 quart pot, over medium heat, heat up the olive oil.
Add in the chicken sausage links and break apart with a spatula as they cook.
After the sausage is browned, but still a little pink, stir in the mushrooms and onions. Break the mushrooms into pieces with a spatula and cook the vegetables until soften.
Stir in the Italian seasoning, ½ teaspoon of salt, pepper, quinoa, Romano cheese, parmesan cheese, drained diced tomatoes, and 1 cup of shredded cheese. Stir all the ingredients together and let it simmer for about 5 minutes. Give the stuffing a taste for seasoning and if it needs more salt stir it in.
Stuff each pepper to the top with stuffing. Divide the rest of the shredded cheese among the stuffed peppers.
Place the stuffed peppers into a 9 x13 dish and pour the chicken stock on the bottom.
Bake for 40 minutes or until peppers are tender and stuffing is heated through. Serve hot.
The peppers can be made completely ahead of time and kept in the refrigerator for up to 5 days. You can also freeze them prepared up to 3 months.
If you freeze the peppers before you bake them then make sure to thaw completely before baking in the oven. You could put in frozen but will need to add on considerable time for them to cook fully. If they are thawed then proceed with cooking instruction but you might need to add on a few minutes if the peppers are cold.