Heat your oven to 200°C/Fan 180°C/Gas 6. Peel and halve the butternut squash. Scoop out the seeds. Chop the flesh into 1 cm cubes. Scatter onto a baking tray. Toss with ½ tbsp oil and plenty of seasoning. Roast in the oven for 30-40 mins till golden and blackened at the edges.
Use a veg peeler to create ribbons of courgette, turning the courgette as you go. Discard the seeded middle. Set the ribbons aside. Finely chop half the sage leaves. Set the rest aside.
Tip half the roasted squash into a food processor with the chopped sage. Keep the rest of the squash warm in a low oven. Blitz to a smooth purée. Tip in the flour and 2 tsp baking powder. Pulse to just combine. Pour in the egg yolk and pulse again for 30 secs. No processor? Press the squash through a sieve. Beat vigorously with the flour, sage and egg yolk.
Bring two pans of salted water to the boil. Scoop out a heaped teaspoon of the squash gnocchi. Shape the sticky dough into rough balls with a second teaspoon. Drop into the water. Add 4 or 5 balls to each pan, then set the timer for 4 mins. The gnocchi will float when they’re cooked.
After 4 mins, lift the gnocchi out and place on a large plate lined with baking paper. Repeat with the remaining dough, using both pans. Take care not to overcrowd the pan with too many gnocchi.
Zest and juice the lemon. Set the zest aside. Whisk the juice with 1 tbsp olive oil. Season and toss with the rocket.
When all the gnocchi have cooked, add the butter to the pan. Add the sage leaves, 2 tsp fennel seeds and lemon zest. Leave the butter to melt and bubble for a couple of mins.
Carefully drop in the cooked gnocchi, roasted squash cubes and the courgette ribbons. Gently toss together to coat the gnocchi. Spoon into a couple of bowls and serve with the dressed rocket salad.