Place the hazelnuts on an ungreased cookie sheet and bake at 350 F. for about 15 minutes. The flesh should be a nice golden brown and the skins should be closer to black in color.Remove from oven and allow to cool completely.
Put the hazelnuts on a dish towel and rub until the skins come off. You may need to help some of them along with your hands, but most of the skins should come off with the towel.
Put the hazelnuts in a food processor and blend until you have a nut butter consistency. It may not be perfectly smooth, but you'll know it when you see it. It takes a few minutes in the processor, so just keep blending.
While the hazelnuts are in the processor, put the chocolate squares in a bowl and microwave for about 3 minutes. Stir, and then continue to microwave in 30 second intervals, stirring after each one, until the chocolate is melted.
Stop the processor and add the chocolate, honey, oil, milk and vanilla. If, after blending, it's not as smooth as you'd like, add a little more milk and oil (in equal amounts), and blend again.
Transfer the nutella to a jar and store in the fridge.
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Notes
Please note that the nutrition data is a ballpark figure. Exact data is not possible.