Preheat oven to 400 degrees. Line with aluminum foil and spray with nonstick baking spray.
Line prepared pan with saltine crackers, salt side up. Crackers should be touching. If you need to overlap the last row of crackers it's okay.
Over medium heat (you can turn the heat up just a touch over medium heat) bring butter and sugar to a full rolling boil while stirring constantly. As soon as mixture comes to a full rolling boil remove spoon, and reduce heat so it's just hot enough to keep the mixture boiling. Set a timer for 3 minutes.
Pour boiled butter/sugar mixture evenly over crackers.
Bake for 5 minutes.
Remove from oven and immediately sprinkle with semi sweet chocolate chips.
Let completely cool. If you want to speed cooling process move candy to a cool place, like the garage!
Once candy has completely cooled move melt white chocolate chips in the microwave by cooking on half power for one minute. Stir. Return to microwave for 15 second intervals, stirring after each interval, until smooth and completely melted.
Add peppermint extract to white chocolate. Working quickly pour over semi sweet chocolate layer, and spread evenly.
Sprinkle with crushed candy canes.
Let completely cool
Cut into squares. Store in an airtight container for up to a week.