Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Grease springform pan (26 cm Ø) and dust with flour. Roughly chop dates. Rinse lemon hot and dab dry.
Finely grate the skin. Halve the lemon, squeeze 1 half. Separate the eggs.
Cream egg yolk, quark, cream, 75 g sugar, sauce powder, lemon peel and 2 tbsp lemon juice with the whisks of the mixer. Beat the egg whites until stiff, adding 75 g of sugar. Add dates to the quark mixture.
Pour into the mould and smooth it down. Bake in a hot oven for 55-60 minutes.
For the syrup, roughly chop the nuts and roast them in a pan without fat. Remove and let cool briefly. Mix with maple syrup.
Carefully remove the cake from the edge with a knife. First let it cool down in the slightly opened oven for about 15 minutes, then take it out and let it cool down. Add nut syrup.