Preheat oven to 350°F.
Toast hazelnuts for about 6-8 minutes on a baking sheet, remove from oven and allow to cool.
Combine all ingredients into a jar or container that can be sealed and stir well to combine.
Close tight and chill overnight or for at least 4 hours.
Serve cold or heated up in the morning.
Add a bit more milk before serving if oats seem a bit dry.