Start by freezing 8 chunks of Nutella in the freezer.
Preheat the oven to 160°C. Prepare two baking sheets with baking paper.
Whip the butter with sugar until it has the consistency of foam. (5 minutes or more)
Add an egg and vanilla extract. Mix until it's well combined.
Add flour, baking soda, baking powder, and salt. Mix well. When the flour starts to disappear, add chunks of chocolate and chocolate chips. Mix again.
Take a piece of cookie dough and flatten it. Grab a frozen Nutella ball and hide it inside the cookie. Repeat the process and put the cookie balls into the freezer for another 30 minutes.
Put 3 cookies on the baking sheet and bake for 13 - 16 minutes (until the edges get brown). I didn't flatten the cookie balls before baking so you can try which version you prefer. Let them rest on the baking sheet for another 20 minutes.
