Add the pitted cherries to a blender, blizz until smooth, then transfer the content to a pan.
Cook on a low to medium heat until it is reduced by half, and it forms a thick sauce, depending on the heat that should take about 10-15 minutes or so.
Beat the egg yolks with the granulated sugar until you get a pale yellow colour.
Separately, bring the the milk, double cream, the seeds from the vanilla pod and the vanilla sugar to a boil, then pour the mixture over the eggs whisking continuously, in order to prevent the eggs from scrambling.
Transfer the whole mixture back to the pan, and cook on a low heat whisking again until it thickens slightly.
Do not overcook, as the mixture will curdle, to test if it is ready, see if it coats the back of a spoon, if it does, take it off the heat and leave to cool completely.
Add the cherry sauce to the milk mixture, then pour everything into a plastic container that has a lid.
You can chop more cherries and scatter over the ice cream mixture.
You can stir the mixture 2 or 3 times every hour or so until it freezes, in order to avoid ice crystals from forming.
If it's too frozen to be scooped, leave outside on the counter for about 30 minutes or so before serving.
Enjoy!