Wilt the spinach, squeeze out the liquid and finely whizz in a processor. Add the basic dough ingredients, plus extra 25g flour and mix to a green pasta. Wrap in cling film and chill for 30 min.
Meanwhile, make the bolognese sauce.
Roll out the dough and cut out 8 lasagne sheets. Cook in boiling water, in batches, for 1 min. Drain.
Line each sheet with the hot bolognese, roll up and put in an ovenproof dish. Top with the cheese sauce and grated Parmesan. Bake at 190°C/fan170°C/gas 5 for 25 min, until golden. Garnish with fresh oregano and serve.