Thaw the spinach leaves and season well with salt and pepper. Bring the milk to the boil, add the processed cheese and stir until smooth. Stir in the roux and cook the sauce for about 1 minute. Mix the spinach, uncooked mini dumplings and bacon in a greased casserole dish and pour the cheese sauce over it.
Bake in a preheated oven at 200 ° (convection 180 °) for about 30 minutes.