Peel and chop the onion. Clean, wash and cut the spring onions into rings. Peel garlic and chop very finely. Peppers clean, wash and cut into fine cubes. Heat oil in a pan and fry onion until transparent.
Add paprika, spring onions and garlic and steam for 8-10 minutes, turning several times. Season with salt, pepper and basil. In the meantime grate cheese finely. Melt the fat in a saucepan. Sauté flour in it until golden brown.
Deglaze with broth. Add cream, bring to the boil and simmer at low heat for about 3 minutes. Stir in 3/4 of the cheese and season to taste with salt, pepper and sugar. Clean, wash and slice the tomatoes.
First, pour some sauce into a greased ovenproof dish. Layer 3 lasagne plates, 1/3 of the vegetables and 1/3 of the sauce in each mould. Do the same with the remaining ingredients. Finish with sauce, cover with tomatoes and sprinkle with the rest of the cheese.
Bake in the preheated oven (electric oven: 175 °C/ gas: level 2) for approx. 50 minutes. Serve garnished with basil as desired.