Why a 1937 Molasses Cookie Recipe Calls for Both Baking Soda and Baking Powder

Food & Drink · Published 3 October 2026 Swipe more like this →

In short: Potato spice cookies from a 1937 cookbook rely on a curious leavening combination. While modern bakers might reach for just one agent, this vintage recipe uses both baking soda and baking powder. Understanding why reveals how molasses interacts with chemistry to create the perfect texture in these classic, hearty treats.

The 1937 edition of Brer Rabbit's New Book of Molasses Recipes features a unique cookie that incorporates boiled potatoes alongside molasses and spices like cloves, cinnamon, and nutmeg. The preparation involves heating molasses and melting shortening into it before adding hot potatoes and dry ingredients. The dough is dropped by half-teaspoons onto oiled paper and baked in a slow oven between 325ºF and 350ºF for 10 to 12 minutes.

A common point of confusion in vintage baking is the simultaneous use of baking soda and baking powder. In this recipe, the molasses provides enough acidity to activate the small amount of baking soda included. However, because the cookies require more lift than that reaction provides, the recipe writer likely added baking powder to ensure sufficient leavening without needing to introduce additional acidic ingredients. Sometimes, baking soda is included not just for leavening, but specifically to enhance the browning of the finished cookie.

The recipe also calls for 'shortening,' a term that has shifted in meaning over time. In 1937, the word referred to any fat solid at room temperature—such as lard, beef fat, butter, or margarine—used to prevent gluten fibers from chaining together, thereby creating a tender texture. While many modern readers assume this refers exclusively to vegetable shortening like Crisco, the original intent was simply to use whatever solid fat was available in the kitchen. Adjusting for the varying water content of these different fats is possible, but for this specific cookie, such precision is unnecessary and risks overthinking the process.

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