Place hazelnuts and cocoa in a food processor and pulse. Add dates, syrup, vanilla, and cinnamon and pulse until everything is mixed.
Spray a muffin tin with nonstick spray (or use coconut oil).
Evenly distribute the hazelnut mixture into the tins, making sure to press down on the bottoms and smooth out the sides either with a spatula or with your hands.
Place tin in the refrigerator for at least 20 minutes, allowing the mixture to harden and take the "cupcake" shape.
For the filling, smash an avocado in a bowl with a fork. Try to get most of the clumps out if you can.
Add cocoa, syrup and coconut oil to the bowl and, using an electric mixer, mix everything together until smooth.
Use a spoon to spoon chocolate mixture into the cupcakes.
Lastly, crush hazelnuts and sprinkle on top of cupcakes.