I have to admit that I've always thought they were snacks for ponies but apparently not! So it seems they are related to the hazelnut and they are a pretty old human snack! According to the Kentish Cobnuts Association they have been enjoyed since around the 16th century and were even used as an early version of conkers.
I found the best way to crack them open was to peel the husk back to expose the nut and use the husk as something to hold onto while bashing the nut with a hammer...people who have a well stocked kitchen might want to use a meat tenderiser or a nut cracker. However you choose to crack the shells, watch out for your fingers!
Once cracked, the cobnuts are quite easy to get out. I had a few duds but that's nature for you!
Once taken out of the shell you get a pale and waxy looking nut that it larger than an almond but more rounded like the hazelnut its related to.
Preheat oven to 150C.
Bake the cobnuts until they are a light golden brown, about 45 minutes.
I ripped up the basil and then blitzed everything with my stick blender (I REALLY need to get one of those little food choppers!) and that was it! You can change the quantities of the ingredients if you prefer your pesto to be a little more garlicky or a bit more cheesy.
Serve with your favourite type of pasta and enjoy!