I blended toasted hazelnuts in a vitamix until they were a butter, added melted chocolate, then added coconut oil to increase smoothness. Here are the amounts:
450 grams hazelnuts (unsalted, raw or roasted)
160 grams chocolate
50 grams coconut oil
Once it was blended, the texture was very smooth and silky.
After a day or two in the refrigerator, the nutella had become grainy.
When you taste it the graininess subsides as it melts in your mouth. This leads me to believe that the graininess is caused by hardened bits of oil, probably the coconut oil.
How can I further emulsify the ingredients to avoid this?