Preheat Oven:
Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.

Cream Butter and Sugars:
In a large bowl, cream the softened butter, peanut butter, granulated sugar, and brown sugar until smooth and fluffy (about 2–3 minutes).

Add Wet Ingredients:
Mix in the egg and vanilla extract until fully incorporated.

Mix Dry Ingredients:
In a separate bowl, whisk together flour, baking soda, baking powder, and salt. Gradually add the dry mixture to the wet ingredients and mix just until combined.

Add Nutella:
For swirled cookies, gently fold Nutella into the dough with a butter knife, being careful not to overmix. For stuffed cookies, chill dough for 30 minutes, scoop a tablespoon of dough, make an indent, spoon Nutella in the center, and seal with more dough.

Scoop and Bake:
Use a cookie scoop or tablespoon to drop dough balls onto the baking sheet. Bake for 9–11 minutes or until edges are set and centers are soft.

Cool:
Let cookies cool on the sheet for 5 minutes, then transfer to a wire rack.