Get your farro or barley cooking- To a small saucepan, add 2 cups of water with one chicken bouillon packet or cube and bring to a boil. Add farro or barley, reduce heat to low, cover and cook 25-30 minutes, or until grain is soft, and most of the liquid is evaporated.
While your farro or barley cooks, broil your peppers. Spray a broiler safe baking dish with cooking spray and pan broil the peppers on high, cut side down for 15 minutes (checking occasionally to avoid burning), or until well-charred/browned. Once broiled, flip peppers over and allow to cool enough to handle before filling. Once peppers are broiled, preheat your oven to 350 degrees.
While your peppers are broiling and your farro or barley is cooking, start the filling. Heat olive oil over medium-high heat and add turkey. Salt and pepper to taste, and continue to cook, breaking the meat up as you go with a wooden spoon or spatula, until all meat is cooked through, about 3 minutes .Reduce heat to medium-low, add chopped mushrooms, season with salt and pepper, and cook, stirring occasionally until mushrooms are reduced in size and most of the liquid evaporates, about 5 mins. Reduce heat to low and add garlic, sun-dried tomatoes, garlic powder, onion powder, dry basil and dry thyme, and stir to combine. Turn off heat and add one cup freshly grated Parmesan cheese and hot cooked farro or barley, and toss to combine.
Fill the peppers with the farro/turkey mixture, top each pepper with a slice of mozzarella and bake for 30-35 minutes, or until cheese is melted and bubbly.
Optional (but yummy!): Broil finished peppers for 1-2 mins to brown the cheese. Serve hot, and top with fresh chopped parsley, if desired.