Pour the cream and milk into a saucepan and bring to the boil. Remove from the heat and let cool.
Put the hazelnuts in a blender and blend them at a low speed, first crumbling them and then transforming them into a more or less soft cream, depending on their oiliness.
Pour the egg yolks in a bowl, add the maple syrup and work with a whisk to incorporate air and make the mixture frothy. Add the cream in a thin trickle, mix well and put it on the stove. Thicken over a low heat stirring constantly. When the mixture begins to make a veil on the spoon, add the hazelnut cream, mix and remove from heat. Allow to cool.
Freeze with the ice-cream maker following the instructions for use. Serve with a dash of maple syrup.