Bring a large pot of salted water to a boil. Once boiling, add spaghetti and cook, stirring occasionally, until al dente, 9-11 minutes. Reserve 1/2 cup cooking water (1 cup for 4 servings), then drain.

Meanwhile, wash and dry all produce. Trim and halve zucchini lengthwise; cut crosswise into 1/4-inchthick half-moons. Dice tomato; toss in a small bowl with a drizzle of olive oil and a pinch of salt and pepper. Quarter lemon. Thinly slice half the chili (if you like spicy food, slice the whole thing). Remove sausage from casings; discard casings.

Heat a large drizzle of olive oil in a large pan over medium-high heat. Add zucchini in a single layer; season with salt and pepper. Cook, stirring occasionally, until browned and tender, 5-6 minutes. Turn off heat; transfer to a plate.

Heat a drizzle of olive oil in same pan over medium-high heat. Add sausage and cook, breaking up meat into pieces, until browned and cooked through, 4-5 minutes. Drain any excess fat from pan. Stir in tomato and a pinch of chili. Cook until slightly softened, about 1 minute.

Add spaghetti, garlic herb butter, 1/4 cup pasta cooking water (1/3 cup for 4 servings), half the Parmesan, and 2 tsp lemon juice (1 TBSP for 4 servings) to pan. Toss until thoroughly combined. (TIP: If needed, add remaining cooking water, a splash at a time, until pasta is coated in sauce.) Stir in half the zucchini and season with plenty of salt and pepper.

Divide pasta between bowls. Top with remaining zucchini and Parmesan. Garnish with a pinch of remaining chili, if desired. Serve with remaining lemon wedges on the side.