Step 1

Prep: Preheat oven to 350°F. Line a baking tray with parchment paper and set aside.

Step 2

Mix dry ingredients: In a medium bowl, stir together flour, baking powder, baking soda, and salt.

Step 3

Cream butter and sugars: In a large mixing bowl, use an electric mixer to beat softened butter until it becomes very creamy. Add the granulated sugar and brown sugar and cream together until fluffy, about 3-4 minutes.

Step 4

Mix in wet ingredients: Add the egg and mix until combined. Finally, add the peanut butter and vanilla extract and mix again until combined.

Step 5

Add dry to wet mixture: Add the flour mixture to the wet mixture and mix until it's almost combined but with some flour patches left.

Step 6

Fold in chocolate: Add the Reese's Pieces and chocolate chunks. Switch to a spatula to fold it all together and finish mixing the dough without overmixing.

Step 7

Scoop cookie dough: Use a 4-tablespoon scooper to scoop out the cookie dough and release it onto your lined baking sheet, leaving about 2" in between each cookie to allow for spreading.

Step 8

Bake: Bake cookies for about 10 minutes. Take them out of the oven and bang the tray against a wire rack a few times to help them spread and flatten. Press a few extra Reese's Pieces and chocolate chunks on top of each cookie. Return them to the oven to bake for another 1-2 minutes, for a total of about 12 minutes.

Step 9

Enjoy warm: Let the cookies cool on the baking sheet for about 10 minutes before carefully transferring them to a wire rack to cool completely or enjoy them warm!