Clean and wash the spinach. Peel and finely chop the onion. Heat oil in a pot. Fry half of the onion in it, add the spinach and let it collapse. Season with salt and pepper.
Clean, wash and chop the peppers. Melt butter in a pot. Brown the paprika and the rest of the onion. Add stock, bring to the boil and simmer for about 5 minutes. Add cream. Season with salt and pepper and puree.
Wash the fish, dab dry and cut into 8 pieces, season with salt and pepper. Put the paprika sauce in a large or 2 small casserole dishes, place the fish pieces in them. Spread spinach on top. Grate cheese and sprinkle over it.
Cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 15 minutes. Remove and sprinkle with pepper.