Note: Have your seafood supplier thoroughly clean, scale and remove heads from the flounders. You may wish to leave the head on if desired. Using a sharp paring knife, cut a slit down center of dark side of flounder from head to tail. Following rib bone, cut a pocket down each side of fish. Rinse fish thoroughly then place in refrigerator until ready to cook. In a small stockpot, poach mirliton and white squash in lightly salted water until fork-tender, take care not to overcook. Strain, cool and set aside. In a 12-inch sauté pan, heat ¼ pound butter over medium-high heat. Add onions, celery, bell peppers and sliced garlic then sauté 3–5 minutes or until vegetables are wilted. Add all squash, tarragon, basil and green onions then sauté 5–7 minutes or until yellow squash is tender but not falling apart. Add shellfish stock, bring to a rolling boil and reduce liquid to 1 cup. Season vegetable mixture to taste using salt, pepper and granulated garlic. Pour contents of skillet into a large mixing bowl then sprinkle in bread crumbs, 1 cup at a time, stirring to absorb stock, but taking care to retain moisture. Note: The stuffing should not be too bready or too dry. Add Parmesan cheese and parsley, stirring well to incorporate. Set aside to cool. When ready to cook, preheat oven to 350°F. Lightly grease a large baking sheet with a 1-inch lip and set aside. Using your fingers, open the pocket created for stuffing and season well with salt, pepper and granulated garlic. Divide stuffing equally among fish and over fill pocket to create a generous mound. Place the stuffed founder on the prepared baking sheet. Season outside of fish with salt, pepper and granulated garlic. Pour an equal amount of remaining butter on each stuffed fish. Bake 25 minutes or until flounder is flaky and stuffing reaches 170°F. Serve immediately.