How to make white chocolate curls:
In a microwavable bowl, heat 4 ounces chopped white chocolate and 1 teaspoon shortening in microwave in 30-second intervals until melted. Stir well to blend.
Turn a baking pan upside down, and spread chocolate mixture on bottom of pan with an offset spatula in straight, lengthwise strokes. Chocolate should be 1⁄16 inch thick or less and cover almost entire bottom of pan. Refrigerate until completely cool, 40 minutes to 1 hour. Remove from refrigerator, and let stand for 2 to 3 minutes.
Working from 1 edge and using a thin flexible spatula, scrape chocolate vertically into curls. If chocolate is too hard, let it sit at room temperature for 1 to 2 minutes. If it gets too soft, return to refrigerator for a few minutes.