Heat the oven to 350 degrees F.
In the bowl of an electric mixer fitted with the paddle attachment, cream butter, peanut butter, and sugars together until light and fluffy. Add egg and vanilla, and mix on medium speed until combined. Sift flour and baking soda together, and add to butter mixture, beating just to combine. Fold in chocolate chunks.
Using a 1 1/2-ounce ice-cream scoop, form dough, and place on a baking sheet lined with a silpat or parchment paper, pressing down slightly to flatten. Bake until golden brown, 18 to 20 minutes. Transfer to a wire rack to cool. Store in an airtight container up to 1 week.
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