Rinse the prawns, defrost and pat dry. Peel onion and garlic. Dice onion, chop garlic. Heat 1 tablespoon of oil in a wide pot with lid. Fry onion and garlic in it.
Add spinach and about 4 tbsp. water. Bring to the boil, cover and defrost according to instructions on the packet. Put spinach in a sieve, squeeze out and drain well.
Stir cream, eggs and cream cheese until smooth. Season vigorously with salt and pepper. Mix the icing and spinach and distribute in a casserole dish. Grate half of the cheese directly on top. Place the prawns on top and the rest of the cheese on top. Bake in a preheated oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer) for approx. 30 minutes until the mixture has set.