Mix Ingredients 1 together until the sugar is mostly dissolved, using a whisk. Then add Ingredients 2 and mix until combined. You can prepare the Nutella filling by scooping it onto a plate and freezing it.

Sift the flour and baking soda together, then fold into the mixture with a spatula until it forms a dough that can be shaped. Add chocolate chips to taste, cover with plastic wrap, and refrigerate for 30 minutes to 1 hour.

Shape the dough into balls, placing a piece of frozen Nutella inside each one. Space them apart on a baking sheet lined with parchment paper.

Bake in a preheated oven at 350°F (180°C) for 10-15 minutes, depending on size (don't let the tops get too hard; the inside should stay soft). Let them cool on a rack, then store in an airtight container.