Lightly oil the cookie sheet and set aside.
Sift the flour, cocoa, and baking soda into the small bowl and set aside.
In the medium bowl, beat together the butter, sugar, and brown sugar, then thoroughly mix in the milk and vanilla. Gradually add the flour until it is completely incorporated and the dough is thick and somewhat dry, like Play-Doh.
Beat together the peanut butter and powdered sugar until the mixture is stiff and no longer shiny. Mix in the chocolate chips and salt.
Preheat oven to 350.
Scoop up a heaping spoonful of the peanut butter mixture and roll into a ball. Set on a plate and repeat with the remaining peanut butter.
Take a piece of chocolate dough a little smaller than a golf ball and roll into a ball, then flatten. Place a peanut butter ball in the middle and wrap the edges of the chocolate dough up and around it, pressing them together to seal the peanut butter inside. Set on the cookie sheet, seam side down, and repeat with remaining dough.
Bake until the surface starts to crack, about 8 minutes. Let cool a bit before eating.