Cream butter and icing sugar together. Add the vanilla. Slowly add in the flour. Divide dough in half and form a square out of each ball of dough. Wrap in plastic wrap and refrigerate for 30 min. to a few hours. If too hard let warm up slightly sitting on the counter.
Preheat oven to 325F. Flour counter surface and rolling pin. Roll dough out to 1/4" thickness and into a rectangle. Trim all sides to have flat edges. Cut the cookies 3/4" wide and 2" long. Place on a cookie sheet with a silpat liner. Bake for 15-18 min. or until edges are just starting to brown. Let cool on cookie sheets for 5 min. then remove to a cooling rack.
When ready to decorate melt the chocolate in the microwave for 30 second intervals stirring between. Line two baking sheets with wax paper. Dip cookies half way into the chocolate and sprinkle on the crushed candy canes. Let dry on the wax paper lined sheets. When tray is full let them set in the fridge. Once set move to a cookie container. Freezes well also for one month covered well.