Peanut Butter FillingRemove butter from refrigerator 2 hours prior to mixing. Cream all together with a paddle attachment. Cookie DoughCombine flour and baking soda. Set aside. Using a paddle attachment on an upright mixer, cream the butter and peanut butter together on #2 speed. Add the sugar and brown sugar to the butter mixture and cream on #3 speed for 4 minutes.... scrape bowl down twice. On #2 speed, incorporate the vanilla and egg slowly, scrape the bowl down. Incorporate dry ingredients and mix on #1 speed ...scrape bowl frequently. Now add peanut chunks and oats on #1 speed. Scrape with an ice cream spoon onto a parchment-lined sheet pan and refrigerate. Bake at 350F for about 10 to 12 minutes until lightly browned.Once baked, place Nutter Butter Filling on top of one cookie and place another cookie on top to form a sandwich. Use enough filling so that it extends to the edges of the cookie.