Preheat oven to 250. Line a 9x13 pan with foil, letting it hang over the sides. Spray foil. Pour the chocolate chips in an even layer on the foil. Place in oven for 5 minutes or until almost melted. Remove from oven, smooth with an offset spatula or knife. Place in refrigerator until cold and firm, about 20 minutes.
Melt white chocolate chips in a double boiler or in a metal bowl over simmering water (don’t let bottom of bowl touch water), until chocolate is almost melted. If you are daring, you can use your microwave. Remove bowl from water and stir until completely melted, stirring in extract. Let cool a little bit so it doesn’t melt the chocolate layer when you pour it on top. Pour this over chocolate layer, and, working quickly, spread to cover. Sprinkle with crushed candy (I pressed the candy in just a bit).
Chill until both layers are firm. Lift foil out of pan and shake off excess candy. Trim edges. Cut into 2” wide strips. Peel bark from foil and cut each strip as desired. Chill in covered container. Makes about 2 pounds.