Bring a large pot of salted water to a boil.
Add rigatoni; cook, stirring occasionally, until al denté (9-11 min)

Reserve 1 cup pasta cooking water then drain and set aside

Wash and dry produce

While pasta cooks:
Trim and halve zucchini lengthways; slice crosswise into 1/4-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 min)

Remove pan from heat; transfer zucchini to a plate

Remover sausage from 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 min)

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 min)

Stir in cream cheese, stock concentrate, 1/2 cup reserved pasta water, 1 tbsp butter, 1/2 tsp sugar, and a pinch of chili flakes to taste.

Remove from heat

Add drained rigatoni and zucchini to pan with sauce. Stir in half the Parmesan. Season with salt and pepper to taste.

Divide between plates, top with Parmesan cheese and serve