Preheat the oven to 200C/400F/Gas 6.
Cook the pasta according to packet instructions. Drain and set aside to keep warm.
Meanwhile, place the squash pieces into a bowl with the olive oil, crushed garlic and two of the thyme sprigs and season with salt and freshly ground black pepper. Mix well to coat the squash, then place the mixture onto a non-stick baking sheet.
Transfer the baking sheet to the oven and roast for 8-10 minutes, or until the squash is tender. Remove the sprigs of thyme and discard.
To serve, stir the roasted squash into the pasta. Place the pasta into a serving bowl, drizzle over a little olive oil and garnish with a sprig of thyme.