Put a large pan of salted water on to boil. Peel and finely slice the shallots.

Put a deep frying pan or wok on a medium heat. Add 2 tsp oil and the shallots. Season with a little salt and pepper and gently fry, stirring often, for 10 mins till the shallots are soft and glossy.

While the shallots fry, trim the courgettes and use a spiraliser to slice them into thin, spaghetti-like strands. No spiraliser? Use a vegetable peeler to peel the courgettes into thin ribbons, peeling down to the seeded core. Once you get to the cores, thinly slice them.

Pick the thick stalks out of the watercress so you just have tender leaves and sprigs. Finely grate the zest from the lemon.

Check the pan of water – it should be boiling by now. Add the spaghetti and simmer for 8-10 mins till the pasta is cooked but still has some bite.

Add the lemon zest to the shallots and flake in the white crab meat. Add 1 tsp Dijon mustard (keep the rest for later) and half the tub of crème fraîche. Keep the heat low and gently warm through, stirring often, for 2-3 mins till the crab sauce is well mixed and warm. Take the pan off the heat for a few mins.

Make a dressing in a large bowl by mixing 1 tsp of the Dijon mustard with 1 tsp olive oil and a squeeze of lemon juice. Season and whisk with a pinch of salt and pepper. Toss the salad leaves in the dressing.

Put the crab sauce back on a low heat and add the watercress. Cook and stir for 2 mins to wilt the cress into the sauce.

Drain the spaghetti and add it to the pan with the courgetti. Use two forks to pick up and drop the spaghetti and courgetti till they're coated in the crab sauce. Divide the pasta and sauce between a couple of warm plates, and serve with the salad. Cut the remaining lemon into wedges and serve on the side for squeezing.