1Heat oven to 375°F. Spray 15x10-inch pan with sides with cooking spray. In resealable food-storage plastic bag, place mints. With rolling pin or flat side of meat mallet, coarsely crush mints. Pour crushed mints into fine strainer; shake lightly so tiny pieces fall into large bowl (reserve larger pieces of mints for garnish).
2In large bowl with tiny mint pieces, stir cookie mix, butter, egg and flour until stiff dough forms. Press into pan. Bake 13 to 15 minutes or until golden brown. Cool completely in pan, about 30 minutes.
3In small microwavable bowl, microwave baking chips and oil on High 30 to 60 seconds, stirring every 15 seconds, until melted and smooth.
4With fork, drizzle half of melted chips over cooled bars. Sprinkle with reserved crushed mints. Drizzle with remaining melted chips. 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.