Start the Traeger on Smoke with the lid open until the fire is established (4 to 5 minutes).
Line a sturdy rimmed baking sheet with parchment paper.
Spread the oats in an even layer on the baking sheet. Place the baking sheet on the grill grate and smoke the oats, stirring once. Remove from the grill. Increase the temperature of the Traeger to 375 degrees F and let it preheat for 10 to 15 minutes.
In the meantime, make the cookie dough: Let the smoked oats cool completely. Lift the sides of the parchment paper up and tip the oats into a mixing bowl. (Return the parchment paper to the baking sheet; you'll reuse it for the cookies.) Add the flour, baking powder, baking soda, and salt and stir to combine. Set aside.
In another bowl - such as the bowl of a stand mixer - combine the butter, peanut butter, and sugar.
Mix on medium-high speed (you can use a hand-held mixer or a wooden spoon and elbow grease) until the mixture is light and fluffy.
Beat in the egg and vanilla. Gradually add the oatmeal-flour mixture using low speed. Stir in the chocolate chunks by hand.
Drop the dough by heaping tablespoons onto the prepared baking sheet and flatten slightly with the back of a tablespoon.
Bake for about 12 minutes, or until the cookies have spread and are lightly browned. Remove the baking sheet from the grill. Let the cookies firm up for a minute or two, then transfer to a wire cooling rack to cool.
Repeat with the remainder of the dough. Store in an airtight container.