In a large mixing bowl, combine butter, sugar and eggs and mix for about 1 minute or until smooth.
Add in Peppermint Schnapps and water and mix until smooth.
In a small bowl, combine your flour, baking powder and salt and whish to blend. Add that to your mixing bowl along with white chocolate chips and peppermint dust/crushed candy canes and mix until blended and smooth.
Line a baking sheet with parchment paper and dust it with flour.
Turn out your biscotti dough onto the baking sheet, (it will be kind of like a ball) and using your hands, shape dough into a long roll shape, about 12-14" long. With your fingers, smack down on the dough so that it ends up being about a ½" high. It will be sort-of like a long rectangle once your are finished.
Bake for 30 minutes, top will begin to crack in spots. Remove tray from the oven and allow it to cool for 5 minutes. Once biscotti had cooled enough to handle (yet are still very warm) Use a sharp chefs knife or long serrated knife and carefully and quickly cut slices on a slight angle into biscotti shape (approximately ½ inch to-¾ inch).
Flip biscotti to one side and bake for an additional 10 minutes.
Remove from oven and gently yet quickly flip biscotti to the opposite side and bake and additional 10 minutes.
Allow biscotti to cool on a cooling rack.
Once biscotti have cooled completely. Melt your chocolate in 30 second bursts in your microwave, stirring after each 30 seconds. Just over a minute total should do it (depending on the strength of your microwave). If some chips are not melted as you stir the chocolate, allow it to sit 15-30 seconds. The residual heat should melt the rest of the chips. Stir till smooth.
Using a small spoon, coat one side of the biscotti with the melted chocolate, smoothing it across with the back of the spoon. Dust each with crushed candy canes as soon as you spread the chocolate on. Allow to cool to allow chocolate to harden. (A cold garage works wonders).
Keep in an airtight container. Biscotti keeps well for weeks.