Heat your oven to 180°C/Fan 160°C/Gas 4. Peel and finely chop the onion. Peel and grate or crush the garlic.
Warm ½ tbsp oil in a pan. Add the onion. Season with salt and pepper. Stir and fry over a low heat for 6-8 mins till soft and glossy but still pale.
Stir the garlic and risotto rice into the onion. Gently cook for 1 min till fragrant. Crumble the stock cube into a jug and pour over 700 ml boiling water. Stir till the stock cube dissolves.
Pour the stock into the risotto rice. Give it a good stir to mix it, then spoon everything into an ovenproof dish. Cover with a lid or a sheet of foil tucked around the edges of the dish. Bake for 30 mins.
Put the tomatoes on a baking tray. Drizzle with 1 tbsp oil. Season. Toss to coat. When the risotto has baked for 20 mins, slide the tomatoes onto the shelf below and roast for 15-20 mins till soft and charred.
When the risotto has baked for 25 mins, uncover and bake for 5-10 more mins to dry out the risotto a little (it should still be creamy and soft). The tomatoes and risotto should finish cooking at the same time.
Meanwhile, warm a dry frying pan over a low heat. Tip in the pine nuts. Toast for 2-3 mins till golden brown. Set aside. Ladle the risotto into warm bowls. Top with the roast tomatoes, a handful of rocket and spoonfuls of ricotta. Scatter with the pine nuts.