Spoon or pipe the Nutella into 12 small portions, about 2 tablespoons each, onto a baking sheet lined with parchment paper. Freeze until firm, at least 1 hour, or until solid enough to handle.

In the bowl of a stand mixer fitted with a paddle attachment, or using a hand mixer and a mixing bowl, add the butter, white sugar, brown sugar, and vanilla. Beat for 1 to 2 minutes, or until light and fluffy. Add the eggs one at a time, beating well after each addition until fully incorporated.

Add the dry ingredients and mix on low speed just until no dry ingredients remain.

Form 12 cookie dough balls, about 50 g each, and place them on a plate. Freeze for 30 to 60 minutes, until firm but still pliable. Alternatively, cover the dough with plastic wrap and refrigerate for up to 4 days.

Preheat the oven to 180C (355F) and line two baking sheets with parchment paper.

Take one cookie dough ball out of the freezer at a time and roll it between two pieces of plastic wrap into a disk using a rolling pin.

Remove one frozen Nutella portion from the freezer and place it in the center of the dough disk.

Wrap the dough around the Nutella, sealing it completely, then roll it gently between your palms to form a smooth ball. Place it in the fridge while you assemble the remaining cookies.

Take 6 assembled cookies out of the fridge and place them on one of the prepared baking sheets, leaving space between each.

Bake one batch at a time, keeping the second batch chilled in the fridge while the first bakes, for 15 to 17 minutes, or until the cookies have spread, puffed up, and are no longer shiny on top. Small, shallow cracks may appear on the surface.