Preheat the oven to 180°C/350°C/gas 4. In a large roasting tray, toss all the vegetables together with the oil and season with salt and pepper. Roast for 30 to 40 minutes, turning once or twice, until sweet and caramelized.
Remove from the oven and, while they’re still hot, mix in the pesto. If you’re serving the vegetables warm then toss the rocket through now so it wilts slightly; if you plan to have it as a cold salad then wait until the veggies have cooled down before adding the rocket. Garnish with Parmesan shavings.