Put a frying pan over a medium heat. Pour in the oil and add the leeks, garlic and a pinch of salt. Cook, stirring occasionally, until collapsed and soft. Meanwhile, bring a pan of water to the boil.

Tip the peas and kale into the pan with the leeks and add a splash of water. Cook until the kale has wilted and peas are defrosted. Turn down the heat to low. Stir in the mustard, crème fraîche and 3/4 of the lemon zest. Add enough water to make a sauce. Give everything a good mix and season to taste.

Drop the lasagne into the water and cook following pack instructions, then drain well. Put one lasagne sheet on each plate, top with half the leek and pea mix then layer up the second lasagne sheet and the remaining greens. Scatter over the remaining lemon zest and add a good grinding of black pepper.