From our partners at Gothamist: A fruit cake from Nellis' Bakery becomes part of the (double) murder mystery Detective Corcoran is trying to solve, but another offering from Nellis' caught our attention: The "Washington cake" that a very hungry Detective O'Brien buys to immediately devour. While O'Brien buys what looks like a two-layered white cake, it turns out there are a few different recipes for "Washington cake," which appears to pay tribute to President George Washington. During the 19th century, Washington was a towering figure in the American psyche and there were celebrations during his birthday. In 1862, a Missouri Democrat said after one such event, "One thought, one sentiment, a single impulse, appeared to move our population on Saturday. It was to render heartwarm homage to the Father of his Country." And when there are parties, there must be cake! The oldest "Washington cake" recipe is from his wife Martha, who made him a huge cake for their anniversary in 1759 and then would make it for their later anniversary and Christmas celebrations. An 1862 book recounted that a former slave of Washington's, Mary Simpson, who lived in New York City would bake the cake every year on his birthday. Here's Mary Washington's recipe: "Take 40 eggs and divide the whites from the yolks and beat them to a froth. Then work 4 pounds of butter to a cream and put the whites of eggs to it a Spoon full at a time till it is well work'd. Then put 4 pounds of sugar finely powdered to it in the same manner then put in the Yolks of eggs and 5 pounds of flour and 5 pounds of fruit. 2 hours will bake it. Add to it half an ounce of mace and nutmeg half a pint of wine and some fresh brandy." That's a big cake! The curatorial staff at Mount Vernon, the Washingtons' home, replicated the recipe ("Where the recipe called for 5 pounds of fruit, without specifying which ones, 2 pounds of raisins, 1 pound of currants, and 2 pounds of apples were used"). There's also a 1780 recipe, as well as some other modern variations. Another version, in an 1852 recipe from "The Ladies' New Book of Cookery: Practical System for Private Families in Town and Country," sounds much lighter, as it doesn't have the fruit (though it does include alcohol) and it includes baking soda. Baking soda would have been a new innovation for American kitchens, as Dr. Austin Church and John Dwight began to manufacture "saleratus," also known as baking soda in 1847. Church and Dwight built a factory in Manhattan, at 25th Street between 10th and 11th Avenues, and that was the birth of the company that makes Arm & Hammer baking soda. There's an alcohol-free cake recipe (but with yeast) from 1860, but a version that involves at least some spices remains the most popular. As for today, there's a Philadelphia bakery, Haegele's, that still makes a beloved Washington cake with a chocolate frosting that makes people reminisce. For more about American cake history, take a look at this timeline from America's Test Kitchen—the Baked Alaska was created at Delmonico's, the classic New York restaurant that opened in 1837, in honor of the new American state.