Brown the Butter
Melt the butter in a saucepan over medium heat. Continue cooking, stirring frequently until the butter turns a golden amber color and develops a nutty fragrance. Remove from heat immediately to prevent burning and transfer to a heat-safe bowl. Allow it to cool completely before using.
Mix Wet Ingredients
In a large mixing bowl, whisk together the brown sugar, granulated sugar, and eggs until the mixture becomes light and fluffy, about 2-3 minutes. This incorporates air into the dough, giving it a better texture.
Add Flavoring
Pour the vanilla extract and the cooled browned butter into the sugar mixture. Mix thoroughly until well combined and smooth. The browned butter adds a rich, caramel-like flavor to the cookie dough.
Incorporate Dry Ingredients
Gradually add the flour to the wet ingredients, mixing at low speed until just combined. Be careful not to overmix as this can develop too much gluten, resulting in a tough cookie texture.
Add Chocolate Chips
Gently fold the chocolate chips into the dough using a spatula or wooden spoon. Distribute them evenly throughout the mixture for consistent chocolate flavor in every bite.
Prepare Baking Dish
Grease a 9-inch pie dish thoroughly or line it with parchment paper, ensuring there's enough overhang to easily remove the cookie pie after baking.
Assemble the Cookie Pie
Press half of the cookie dough into an even layer on the bottom of the prepared dish. Carefully spread the Nutella over this base, leaving about 1/2 inch from the edges. Cover with the remaining cookie dough, sealing the edges well to prevent the Nutella from leaking. If using, sprinkle extra chocolate chips on top.
Bake to Perfection
Place in a preheated 350°F (180°C) oven and bake for 35-40 minutes until the edges are golden brown and the center is slightly soft. The center will continue to cook as it cools.
Cool and Serve
Remove from the oven and allow the cookie pie to cool for at least 20 minutes before slicing. For best results, serve while still warm with a scoop of vanilla ice cream or a drizzle of chocolate sauce.