This recipe is compliments of Liz Driver, of The Cookbook Store in Toronto, who is also a culinary historian and the author of Culinary Landmarks: A Bibliography of Canadian Cookbooks, 1825-1949 (University of Toronto Press).
Icebox cookies became popular with the introduction of electric refrigerators in the 1930s.
For shredded almonds, simply grate whole almonds on a metal grater. We prefer unsalted butter for baking and compensated by adding 1 teaspoon of kosher salt to the flour mixture.