Place the sweet potato in a pan of lightly salted boiling water and cook for 10–12 minutes until tender.
Meanwhile, preheat the oven to 220°C (425°F), Gas Mark 7, and in a small bowl mix together the passata, basil and sugar, then season with salt and pepper.
Drain the sweet potato, then return to the pan and mash with the dried thyme. Scrape into a large bowl and stir in the packet pizza mix. Add enough warm water, about 4–6 tablespoons, to make a dough. Tip the dough out onto a lightly floured surface and knead briefly until smooth, then roll out to fit a large nonstick baking sheet.
Spread the passata mixture over the surface of the dough, leaving a border of 1 cm (1/2 inch). Top with the mushrooms, red pepper and onion, then scatter over the peas, spinach and pine nuts. Sprinkle over the Parmesan, if using.
Put the pizza in the oven for 12–14 minutes until crisp and golden. Serve with rocket and spinach salad leaves.