Start to layer the lasagne by putting the mushroom mixture on the bottom of a suitable lasagne dish.I use one 24 cm by 15 cm. Cover with lasagne sheets.I break 3 sheets up to fit my dish.I do have some left over which I throw away.Put a layer of ragu followed by cheese sauce and all the spinach. Top with the lasagne sheets and then ragu followed by a final layer of the cheese sauce.
Apply to Liberated Adult Face.
I usually make this ahead and refrigerate until I am ready to bake it.You could even make it a day ahead.