Step 1: Prepare the Nutella Filling

1. Line a baking sheet or plate with parchment paper.
2. Scoop small dollops (about 1 teaspoon each) of Nutella onto the parchment paper.
3. Freeze for at least 20-30 minutes until firm.

Step 2: Make the Cookie Dough

1. In a bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
2. In a large mixing bowl, cream the softened butter, granulated sugar, and brown sugar until light and fluffy.
3. Beat in the egg and vanilla extract.
4. Gradually mix in the dry ingredients until just combined.
5. Fold in the chocolate chips.

Step 3: Assemble the Cookies

1. Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. Scoop about 1 ½ tablespoons of cookie dough and flatten it slightly in your hand.
3. Place a frozen Nutella dollop in the center of the dough and wrap the dough around it, sealing the edges completely.
4. Place the stuffed dough balls on the prepared baking sheet, spaced about 2 inches apart.

Step 4: Bake

1. Bake the cookies for 10-12 minutes until the edges are set but the centers still look slightly soft.
2. Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely (if you can resist!).