Place chocolate + oil in a large, microwave safe bowl and melt in the microwave (I usually do 1 minute on High, but microwaves are funky so keep an eye on things). Stir the chocolate to get rid of any chunks. Sometimes it will look chunky, but if you give it 20 or so stirs, you’ll get rid of all of the chunks without overheating it. Set it aside to cool a beat. Whisk in the eggs, brown sugar, granulated sugar and vanilla. This mixture will be thick…don’t panic. Set aside.
In another bowl whisk together the bread flour, all-purpose flour, cocoa powder, baking powder and baking soda and sea salt. Pour the flour mixture into the chocolate mixture and stir until just combined. Wrap tightly and chill the cookie dough for 30 minutes in the fridge.
Preheat your oven to 375 degrees F. Line your baking sheets with parchment paper.
Roll 1 1/2 tablespoons of dough and place on the baking sheet allowing at least two inches between dough balls. Freeze for 10 minutes or place in the fridge for 20 minutes. If you have a small freezer, you could set them on a dish and then transfer to your baking sheet.
Bake for 10 minutes in the center of the oven. You want to slightly under bake these. Allow the cookies to cool on the sheet for 5-10 minutes, or until they come off easily, and transfer to a rack to finish cooling.
In a medium bowl stir together the powdered sugar, soft butter, peppermint extract and milk until smooth. Add more milk if necessary to get desired consistency: thick, but spreadable. Schmear on top of the cooled cookies, decorate with your favorite sprinkles and exchange away.