Peel and wash the potatoes and carrots and slice them into thin slices. Line a gratin dish with them and season with salt and pepper. Peel the cucumber, halve it lengthwise and remove the seeds. Cut the cucumber into thin slices.
Peel and chop the onion. Wash and chop the dill. Heat the fat. Brown onion and cucumber in it. Season with salt and pepper. Deglaze with broth, bring to the boil briefly. Stir in the cream and dill, let it cool down a little, season again.
Whisk the eggs, also stir in. Spread on the vegetables. Sprinkle with cheese and bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 40 minutes. Serve garnished with dill flags.