Add the milk and cream and vanilla to a pan and bring to a simmer. (if using a vanilla pod once it reaches a simmer pour into a bowl and cover with some plastic wrap touching the surface and leave to infuse for a few hours or over night in the fridge then bring back to a simmer again when you are ready to make it, if using paste then you can make the base in one go and go on the the next step right away)
While the milk is heating up in a bowl mix the egg yolks and sugar, once the milk has just began to boil, slowly pour 1/4 of the hot milk/cream over the egg yolks while whisking constantly. then pour in the rest while still whisking and return it all back into the pan,
Add the mascarpone and a pinch of salt and whisk until you get a thick custard. pour into a bowl and cover with plastic wrap so it touches the surface of the custard so a skin doesn't form.
Leave to cool, then chill in the fridge overnight, alternatively if your ice cream machine has a pre chill setting you can use that