juice and grated rind of 1/2 lemon, plus extra rind to garnish
50 g (2 oz) rocket leaves
Place the onion and butternut squash in a roasting tin and drizzle with the oil. Bake in a preheated oven, 220°C (425°F), Gas Mark 7, for 15 minutes or until golden and softened.
Meanwhile, cook the lasagne sheets in a large saucepan of boiling salted water for 7–10 minutes or until soft, then cut each sheet in half. While the pasta is cooking, mix together the ricotta, mascarpone and lemon juice and rind in a small bowl.
Place 1 half-sheet of lasagne on each of 4 serving plates, top with some squash and onion, then add some of the ricotta mixture. Repeat the layers until all the pasta is used up. Scatter over the rocket and lemon rind and serve immediately.