For the cheese mixture, mix 400 g cream cheese, sour cream and 200 g sugar with the whisks of the mixer until smooth. Gradually stir in 2 tablespoons of flour, 2 tablespoons of lemon juice and 4 eggs. Put the mixture aside.
Peel, wash and finely grate the carrots. Mix with 2 tablespoons lemon juice. Grease a springform pan (26 cm Ø). Preheat the oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer).
For the carrot dough, whisk 200 g butter, 200 g sugar, vanilla sugar and 1 pinch of salt until creamy. Stir in 3 eggs one after the other. Mix 200 g flour, nuts and baking powder, add and stir in briefly.
Fold in the grated carrots.
Put about half of the sponge mixture into the springform pan and smooth it down. Pour about half the cream cheese mixture on top. Carefully spread the rest of the dough on top (it does not have to be spread to the brim), add the rest of the cream cheese mixture.
Using a fork, pull several times spirally through the dough. Bake in a hot oven for about 1 hour.
Remove from the oven and allow to cool on a cake rack in the mould. For the cinnamon sauce, stir 200 g cream cheese, milk, 1 tablespoon sugar and cinnamon until smooth. Remove the cake from the tin and serve with the sauce.