Brown Butter Nutella Stuffed Cookie Bars

0 Prepare the Nutella Layer: Line an 8x8-inch pan with parchment paper. Spread the Nutella into a thin, even square that fits the pan. Freeze for 30-40 minutes or until solid.
1 Brown the Butter: In a small saucepan over medium heat, melt the butter. Continue cooking, stirring often, until it turns golden brown and smells nutty. Remove from heat and let it cool slightly.
2 Make the Cookie Dough: In a large bowl, whisk together the browned butter, brown sugar, and granulated sugar. Stir in the egg, egg yolks, and vanilla until smooth.
3 In a separate bowl, whisk together the flour, baking soda, and salt. Add the dry ingredients to the wet and mix until just combined. Fold in the chocolate chips.
4 Assemble: Press half of the cookie dough into the bottom of the lined 8x8-inch pan. Place the frozen Nutella square on top. Carefully press the remaining cookie dough over the Nutella layer, covering it completely.
5 Bake: Preheat oven to 350°F (175°C). Bake for 25-30 minutes or until golden brown and set.
6 Cool & Serve: Let the bars cool in the pan for at least 30 minutes before slicing. Sprinkle with flaky sea salt if desired. Enjoy!