2Cut a 3/4-inch-thick slice lengthwise down the center of each zucchini to make four "boats." Use a spoon to scoop out flesh from each zucchini boat, leaving a 3/8 inch shell intact all around. Dice two zucchini slices and set aside.
3Heat oil in a skillet over medium heat. Add sausage and cook, breaking it up with a spoon, until crumbly and starting to brown, about 8 minutes. Stir in pepper flakes, salt, and pepper. Add diced zucchini, onion, and garlic; cook and stir until onion is translucent, about 5 minutes.
