Add the sugar, milk, butter and dark cocoa powder to a saucepan over medium heat (for gooey cookies you do NOT want to let the mixture boil) until the butter melts.
Add the peanut butter and vanilla extract and stir until the peanut butter is blended into the chocolate mixture. Remove from heat and add 3 cups of the oats. If the mixture still seems too runny, gradually add more oats until it's a nice thick consistency.
Drop by tablespoons onto wax paper or Silpat Mat and let cool until set. Keep in a tightly sealed container in the fridge!
** Nutritional information is an estimate and may vary.