If you're cutting these to add to a cookie tray or serve to a crowd, here are my tips on getting clean, even squares: Let the cookie bars cool all completely to room temperature before cutting.  Use a very sharp, long knife.  Dip the knife in warm water and quickly dry it off before the first cut. Then wipe it clean, dip it in warm water, then dry again before each subsequent cut.  Use a ruler to measure equal pieces. If cutting these cookie bars into 16 squares, you'd want each bar to be 2" x 2."