Wash and dry produce.

Bring a large pot of salted water to a boil. Once water is boiling, add rigatoni; cook, stirring occasionally, until al dente, 9-11 minutes.

Reserve 1 cup pasta cooking water (1½ cups for 4 servings), then drain and set aside.

Meanwhile, trim and halve zucchini lengthwise; slice crosswise into ¼-inch-thick half-moons. Peel and mince or grate garlic. Quarter lemon.

While pasta cooks, heat a drizzle of oil in a large pan over medium-high heat. Add zucchini; season with salt and pepper. Cook, stirring occasionally, until browned and tender, 5-6 minutes. Remove pan from heat; transfer zucchini to a plate.

Remove sausage* from casing if necessary; discard casing. Heat another drizzle of oil in same pan over medium-high heat. Add sausage to pan and cook, breaking up meat into pieces, until almost cooked through, 3-4 minutes (it’ll finish cooking in the next step).

Stir garlic and tomato paste into pan with sausage; cook until garlic is fragrant, tomato paste is well distributed, and sausage is fully cooked, 1-2 minutes.

Stir in cream cheese, stock concentrate, ½ cup reserved pasta cooking water (ladle straight from the pot if pasta hasn’t finished cooking yet), 1 TBSP butter, ½ tsp sugar, and a pinch of chili flakes to taste. (For 4 servings, use ¾ cup reserved pasta cooking water, 2 TBSP butter, and 1 tsp sugar.) Remove from heat.

Add drained rigatoni and zucchini to pan with sauce. Stir in half the Parmesan. Season with salt and pepper to taste. TIP: If needed, stir in more reserved pasta cooking water a splash at a time until pasta is coated in a creamy sauce.

In a large bowl, whisk together juice from half the lemon (whole lemon for 4 servings), 1 TBSP olive oil (2 TBSP for 4), salt, and pepper. Add arugula and toss to coat.

Divide pasta between bowls and top with remaining Parmesan. Serve with arugula salad and any remaining lemon wedges on the side.