Thaw or cook the spinach in the pot so that it disintegrates nicely. Then add the tomatoes and chop them up with a spoon. Mix in the tuna. Add about 2-3 tablespoons of cream cheese, or more if you like. Season well and bring to the boil briefly. It shouldn`t be too watery or too dry, but nice and creamy.
Layer alternately spinach and lasagne sheets in a baking dish. 3-4 layers, start and finish with spinach. Finally, sprinkle the cheese on top. If you want, you can also put some fresh tomato slices on top.
Bake in the oven for 20-30 minutes until the cheese is golden brown and the lasagne sheets can be easily pierced with a knife.
If you don`t like tuna, you can just leave it out. Tastes just as good.