Scoop heaped teaspoons of Nutella onto a lined tray, and freeze until solid. This usually takes 30-60 minutes
Once the Nutella has frozen, make the cookie dough
Preheat the oven to 190C/170C Fan
Beat together the butter and sugar until fluffy, and then add in the vanilla and egg and beat again until smooth.
Whisk together the flour, salt, bicarbonate of soda and cornflour, and then add in to the other mix.
Add in the finely chopped chocolate and mix until combined.
Scoop the cookies with a 5cm cookie scoop to portion (or split into 15)
As you scoop each cookie, flatten the dough slightly into a disc shape, and add a frozen lump of Nutella to the middle and then wrap the cookie dough around the Nutella fully so its covered
They will be balls of cookie in the end
Line 2-3 LARGE trays with parchment paper - and add 6 cookies to each tray. Each cookie might spread a bit whilst baking, so you want room for them to grow!
Bake in the oven for 11-13 minutes, or until golden. The more you bake, the less gooey they will be!
Notes
Honestly though, just imagine making a batch of these, leaving them to cool for a couple of minutes so that you don't burn yourself (trust me, straight from the oven is a mistake), but then having a nice cup of tea, and a warm gooey Nutella stuffed cookie on the side. Okay, maybe a few of them... enjoy!