Heat your oven to 200°C/Fan 180°C/Gas 6. Scrub the potatoes and cut into chips the thickness of an index finger. Scatter the chips onto a large baking tray and pour over 1 tbsp olive oil. Sprinkle with a generous pinch of salt and pepper and toss to coat. Slide the chips into the oven and roast for 40 mins, turning halfway, till golden and crispy.

Trim the root and any ragged ends away from the spring onion. Thinly slice the spring onion. Grate the zest from the lemon. Finely chop the parsley leaves and stalks. Finely grate the Parmesan.

Pop the butter into a pan and melt over a medium heat. Slide in the sliced spring onions and cook for 2 mins, till softened. Sprinkle in a pinch of salt and pepper. Remove from the heat. Scoop the crab meat into the pan (keep the shells for later). Add the chopped parsley and half of the grated Parmesan. Stir in the lemon zest and sprinkle in a pinch or two of cayenne pepper (cayenne is hot, so use as much or little as you prefer).

Spoon the crab meat back into the crab shells and scatter over the remaining Parmesan. Put the stuffed shells onto a baking tray and slide into the oven onto the shelf below the chips. Bake for 15 mins, till bubbling and cooked through.

Meanwhile, toss the rocket leaves into a bowl. Squeeze over half of the lemon juice and drizzle over 1 tbsp olive oil. Tos to mix.

Serve the crabs and chips with the lemony rocket salad on the side, with an extra pinch or two of cayenne sprinkled on top and wedges of the remaining lemon half on the side for squeezing.