Start by preheating your oven to 350°F (175°C). Line a baking sheet with parchment paper to prevent sticking. This step ensures the cookies bake evenly and release easily after baking.
In a microwave-safe bowl, melt the butter in short bursts until fully melted. Stir the peanut butter into the warm butter until smooth. This mixture forms the rich base of the cookie dough.
Add the brown sugar and granulated sugar to the butter mixture. Whisk everything together until smooth and well combined. Let the mixture cool slightly before adding other ingredients.
In a separate bowl, combine the flour, baking soda, baking powder, and salt. Mixing dry ingredients separately ensures they distribute evenly throughout the cookie dough.
Combine Wet Ingredients
Add eggs, milk, and vanilla extract to the cooled butter mixture. Whisk until the mixture becomes smooth and creamy. This step helps build the flavor and texture of the cookies.
Gradually add the dry ingredients to the wet mixture. Stir gently with a spatula until a thick cookie dough forms. Avoid overmixing so the cookies stay soft.
Scoop portions of dough and roll them into balls. Make a small indentation in the center with your thumb. Add a teaspoon of Nutella into the center of each dough ball.
Carefully fold the dough edges slightly over the Nutella so it stays inside but remains partly visible. Place the dough balls on the prepared baking sheet with enough space between them.
Bake the cookies for about 14 minutes until the edges become lightly golden. The centers may look slightly soft, but they will firm up as they cool.
Allow the cookies to cool on the baking sheet for about 5 minutes. Transfer them to a cooling rack to cool completely. This helps maintain their chewy texture.