03Heat the remaining extra-virgin olive oil in a skillet over medium-high heat and saute the mushrooms, onions and garlic for 5 minutes. Add in the reserved zucchini and tomatoes, season with salt and pepper, to taste and heat through for 1 minute, then remove from the heat.04While the veggies cook, toast the bread in a toaster, then spread liberally with butter and tear into pieces. Add the bread to a food processor along with the parsley and tarragon or basil, and pulse into herb crumbs.05Fold the herb crumbs into the veggies along with 1/2 cup Parmesan and the egg. Mound the zucchini stuffing in to the shells and roast for 15 minutes. Remove from the oven, sprinkle the tops with remaining cheese and broil for 2 to 3 minutes to brown.