1. Place 24 heaping tsp of nutella on a plate or small baking sheet lined with parchment paper; freeze for at least 1 hour until solid.
2. In a large bowl, beat together the butter, coconut sugar and brown sugar for 2-3 minutes; mix in the eggs and vanilla.
3. Mix in the flour, cocoa powder, baking soda and kosher salt and then refrigerate the dough for at least 30 minutes (Don't skip this step! The dough will be too sticky if it is not refrigerated).
4. Preheat the oven to 350°F and line 2-3 baking sheets with parchment paper; remove the dough and nutella from the fridge / freezer.
5. Press a heaping Tbsp of cookie dough into a flat patty shape and place the frozen nutella in the middle; seal up the corners so the nutella is enclosed and roll into a ball.
6. Place cookie dough balls on a baking sheet 2" apart; sprinkle with flaky sea salt and bake for 15 minutes - enjoy!