Melt the butter in a pan and heat until it starts to foam. Add the flour and cook for 1 minute, then gradually add the milk, whisking after each addition to make a nice thick sauce. Season with salt and pepper.
Preheat the oven to 180 C, Fan 160, Gas 4.
Heat the spinach with 2 tbsps water in a large pan for about 2 minutes until it wilts. Remove and set aside to cool then squeeze out as much moisture as you can.
Take an ovenproof dish measuring about 30 x 20 cm and spread a ladleful of white sauce over the bottom Cover with some sheets of lasagne.
Add some spinach and rocket, then a sprinkling of goats cheese. Continue building up the layers finishing with lasagne then pour the rest of the white sauce on top.
Sprinkle with pine nuts and parmesan.
Bake in the preheated oven for 30 minutes until golden and bubbling.