Line a baking sheet with parchment paper and drop small spoonfuls of Nutella on it. Freeze for at least 30 minutes.

In a medium bowl, whisk together flour, baking soda, and salt.

In a large bowl, mix melted butter, brown sugar, and granulated sugar until smooth.

Add the egg, egg yolk, and vanilla extract. Stir until combined.

Gradually add the dry ingredients to the wet ingredients and mix until a dough forms.

Fold in the chocolate chips.

Scoop dough into balls, flatten slightly, and place a frozen Nutella piece in the center. Wrap the dough around to seal.

Place cookie balls on a parchment-lined baking sheet and chill for 15–20 minutes.

Bake at 350°F (175°C) for 10–12 minutes or until golden around the edges.

Cool on the baking sheet for 5 minutes before transferring to a wire rack.