For the cookies, in a large bowl or mixer, combine together the butter, peanut butter and sugars and let them beat for 3-5 minutes, or until smooth. Add the eggs one at a time and then the vanilla, soda, powder, and salt. Add the flour to the mixture and continue to mix on low speed until the cookie dough is combined. Place the cookie dough in the fridge for 15-30 minutes or until cold. Remove the cookie dough from the fridge and preheat your oven to 375 degrees. Use a tablespoon to spoon out equal size cookie pieces. Roll into a ball and roll in the 1/3 cup of sugar until the ball is covered in sugar. Place 12 balls on a cookie sheet and fork the cookies creating a square pattern. Bake cookies for 6 1/2 minutes, or until lightly browned. While the cookies are baking, make the filling.
For the filling, place the butter and peanut butter into a bowl and mix with an electric mixer until combined and smooth. Add the vanilla, salt, milk and powdered sugar. Beat together until smooth and the frosting is to your desired texture. If the frosting is too thick, add a little more milk. If too thin, add a little more sugar. Once the frosting is whipped smooth and the right consistency, fold in the marshmallow cream and combine until thoroughly mixed (you can whip with the beaters if you would like). Cool the cooked cookies on a cookie sheet. Once they are cool, put a tablespoon of the filling on the bottom of one cookie. Place another cookie on the other side of the filling, creating a sandwich.