Combine the butter and sugar in a mixing bowl and cream on medium-high speed for about 2-3 minutes. Add in the flours, evaporated milk and vanilla.
Slowly stir in the p.b. cups and chocolate, a little bit at a time. Cover the bowl with plastic wrap and refrigerate for about an hour. (You'll want the mixture to harden enough so you can make balls.).
Use a small cookie scoop (like an ice cream scoop) or spoons to shape the chilled cookie dough mixture into balls. Place on a wax-paper-lined baking sheet and freeze for 1-2 hours.