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.

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 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.

Divide between bowls; top with remaining Parmesan and serve.