As a first step to prepare our tiramisù with ricotta , dip half the ladyfingers in coffee and arrange them on a round bowl.
With an immersion blender we work the ricotta with the sugar and vanillin, we should obtain a smooth cream without lumps, then add the dark chocolate, previously coarsely chopped, to the mixture.
Then cover the first layer of ladyfingers with half of the ricotta cream. We then arrange a new row of ladyfingers, always wet with coffee and coat everything with the other part of the ricotta cream, level with a spatula and sprinkle with cocoa.
Before serving our ricotta tiramisu let it harden for a few hours in the fridge.