In a medium-size glass bowl, melt the chocolate and vegetable shortening together in 30-45 second increments until just the vegetable shortening has melted completely and is hot. Stir together until the chocolate is melted and smooth. If needed, microwave again for only 15 seconds.
3 oz Chocolate, 1 tablespoon Vegetable Shortening
Pour the melted chocolate over the underside of a cookie sheet or jelly roll pan. Then spread out into a thin layer using an offset spatula.
Carefully place the cookie sheet or pan into the freezer for approximately 4 minutes. You want the chocolate to be in the sweet spot where it's not too soft and it's not rock hard where it will break the minute you try to create the curls. A good indication that it is ready is it will no longer be shiny in appearance and the tip of your finger—when gently touching the chocolate—will leave a subtle print and not a dent.
Hold the putty knife or bench scraper in your dominant hand at about a 45 degree angle starting at the bottom of the pan. Then with your other hand, brace the back of the cookie sheet or jelly roll pan. Gently push forward to get the curl going and stop when you're satisfied with how the curl looks. You can push the whole way across the pan for a larger curl or you can stop every so many inches. Carefully transfer the curl to a plate using either your fingers or tweezers.
Repeat until you have all your chocolate curls transferred over to a place, then place them in the freezer for 15-20 minutes to harden. You can also place them in the refrigerator as well, but it may take a smidge longer.