Heat oven to 350 degrees F. In resealable food-storage plastic bag, place mints. With rolling pin or flat side of meat mallet, coarsely crush mints.
In ungreased 15x10x1-inch pan, break up cookie dough. In fine strainer and over dough, pour crushed mints; shake lightly so tiny pieces fall onto dough (reserve larger pieces of mints for garnish). With hands, knead tiny pieces of mints into dough; press dough in bottom of pan.
Bake 14 to 16 minutes or until golden brown. Cool completely, about 10 minutes.
In small microwavable bowl, microwave vanilla baking chips and oil on High 30 to 60 seconds, stirring every 15 seconds, until melted and smooth.
With fork, drizzle half of melted chip mixture over cooled bars. Sprinkle with reserved crushed mints. Drizzle with remaining melted chip mixture (if mixture begins to firm up, microwave 10 to 15 seconds). Let stand until set, about 10 minutes. Break into irregular 2- to 3-inch pieces. Store between sheets of waxed paper in tightly covered container.
Cut this bark into bars instead of breaking it into pieces, if desired.