Step 1Cook pasta in a saucepan of boiling water, according to packet directions, or until al dente. Drain and keep warm.
Step 2Meanwhile, heat the olive oil in a large non-stick frying pan over medium-high heat. Sauté onion and garlic for 3–4 minutes, or until softened. Add the thyme leaves and cook for a further minute, or until fragrant.
Step 3Add flour to pan and stir to coat onions. Gradually add milk, stirring constantly, until smooth. Bring mixture to the boil, over a medium heat. Cook, stirring, for 4–5 minutes, or until thickened. Add zucchini and squash and cook, stirring, for 2–3 minutes, or until vegies are just tender.
Step 4Add spinach and parmesan and cook, stirring, for 1 minute, or until spinach wilts. Add pasta and toss to coat. Divide the pasta among 4 bowls and season with cracked black pepper.