How to prepare hazel nuts?

I tried making broccoli pesto yesterday, and stumbled over having to add hazel nuts. I’ve never done anything with them, but figured I’d just buy them and look up what to do with them.

Looking around the internet, I drew the conclusion that I had to heat them in the oven for a while and then remove the shell with a towel or something. However, when I took them out of the oven after the specified time, they were completely black, and didn’t come out of the shell easily.

I finally just grabbed a hammer to break the shell, and took out the insides (including the brown skin, of which I had no idea how to remove them) which I then used in the pesto. To prevent this in the future, does anybody know what the correct way of preparing hazel nuts is?