In a medium bowl, combine sifted flours with baking soda and salt. Gently hand whisk together and set aside.
In the bowl of a stand mixer fitted with paddle attachment on medium, cream together softened butter with granulated and dark brown sugar until fluffy. About 2-3 minutes. Add peanut butter and mix until smooth. (scrape bottom and sides of bowl as needed.)
Add lightly beaten egg and vanilla extract to the butter and sugar. Mix until incorporated.
Spoon flour mixture into butter mixture and mix until just incorporated. Don't over work the cookies dough. (scrape bottom and sides of bowl as needed)
Fold in chocolate chunks with a spatula or wooden spoon.
Take a 3Tbsp Ice Cream Scoop and measure out 12 large cookie dough balls. Place the dough balls on a parchment paper lined cookie sheet. Chill the entire plate in the fridge for 30-40 minutes until each ball is firm.
Preheat oven to 350 F and line an additional cookie sheet with silicone mat or parchment paper.
Then, divide the cookies onto two prepared cookie sheets and arrange the cookie dough balls 2-3 inches apart.
These cookies will spread on their own while baking. But they don't flatten all the way when the dough is super cold (plus they are BIG cookies!). I prefer to bang them on the counter partly through baking to create that signature jumbo flat cookie look!
At the 10-12 minute mark, remove tray from oven. Simply keep the tray of half baked cookies flat, give it a downward medium bang on the counter and watch those cookies flatten and crinkle!!
Return the tray to the oven and finish baking for an additional 3-4 minutes. The total bake time on the cookies should be 15-17 minutes.
DO NOT OVER BAKE the cookies!!! Once you seem them start to get darker brown on the edges, take them out of the oven. They will continue to firm while cooling on cookie sheet.
Place cookie sheet on cooling rack for 20 minutes. Then, remove cookies individually from tray and cool completely on rack.
**Please read tips in the body of post for extra notes on recipe.