Preheat oven to 500 degrees or broiler to high with rack 3-4 inches from flame. Bring a large pot of salted water to a boil. Wash and dry all produce. Trim zucchini, then slice into 1/3-inch-thick rounds. Halve, peel, and finely dice onion. Trim and thinly slice scallions, separating whites from greens. Mince or grate garlic.

Spread out zucchini on a lightly oiled baking sheet. Top with a large drizzle of oil. Season with 1 tsp Tuscan Heat Spice (save the rest for step 4) and plenty of salt and pepper. Bake or broil until browned, 5-7 minutes. (TIP: Keep an eye out for any burning.) Transfer zucchini to a medium bowl and reduce oven temperature to 450 degrees.

Once water boils, add gemelli to pot. Cook until al dente, 9-11 minutes. Reserve 1 cup pasta cooking water, then drain. Meanwhile, heat a drizzle of olive oil in a large pan over medium-high heat. Add sausage and cook, breaking up meat into pieces, until cooked through, 4-6 minutes. Remove from pan and set aside in another medium bowl.

Heat another large drizzle of olive oil in same pan over medium-high heat. Add onion and scallion whites. Cook, stirring, until softened, 2-3 minutes. Add garlic and remaining Tuscan Heat Spice. Cook until fragrant, about 30 seconds. Add tomatoes, stock concentrate, and 1/2 cup reserved pasta cooking water. Bring to a boil, then lower heat and reduce to a simmer. Season with plenty of salt and pepper.

Place flatbreads on baking sheet used for zucchini. Spread each flatbread with about 1/3 cup sauce. Evenly sprinkle with mozzarella, then arrange half the zucchini and half the sausage on top. Bake until cheese melts and crust is golden brown and crisp, 5-7 minutes. Cut into slices, sprinkle with half the scallion greens, and serve.

To prep lunch, place pan with remaining sauce over medium-low heat. Stir in 2 TBSP butter and sour cream. Add more pasta cooking water, if needed, to loosen. Stir in gemelli along with remaining sausage, zucchini, and scallion greens. Divide between reusable containers. Pack with Parmesan and keep refrigerated. When ready to eat, microwave on high for 2-3 minutes, then sprinkle with Parmesan.