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The chocolate cake that fueled the Manhattan Project

Posted November 24, 2021 7:06 p.m. EST
Updated November 25, 2021 7:53 a.m. EST

Edith Warner's famous chocolate cake that helped fuel the Manhattan Project (image courtesy National Security Research Center)

If you are looking for something to fill an empty spot on your Thanksgiving dessert table or would like to celebrate National Cake Day on Nov. 26, consider the chocolate cake that helped usher in the nuclear age according to Patty Templeton, archivist for the National Security Research Center and Los Alamos National Laboratory.

It was 1942, and Physicist J. Robert Oppenheimer was assembling hundreds, ultimately thousands, of scientists and engineers on "Project Y," an isolated Mesa 34 miles north of Santa Fe, New Mexico, in what would become the instant city of Los Alamos.

Teams worked in secrecy six days a week in a race to harness atomic power before Adolf Hitler did.

Histories of the Manhattan project mention scientists like Niels Bohr, who made foundational contributions to the understanding of the structure of the atom; Richard Feynman, who paved the path to the field of quantum mechanics today; and Enrico Fermi, who created the first atomic reactor and is known as the "architect of the atomic bomb."

But you'll find mention of Edith Warner, and the spirit-lifting meals she served from her little pueblo house next to the bridge that crossed the Rio Grande River, on the San Ildefonso Pueblo reservation.

Edith Warner's tea house at the Otowi Crossing

Throughout the war, she served five to six couples a night at $2 a head and did not accept tips. Warner had no phone, so in-person reservations were required, booked weeks in advance.

Warner worked 16-hours a day serving her guests garden-to-table feasts of stewed meats flavored with wild herbs and vegetables from her garden which included ten varieties of squash. Every meal was finished with her famous chocolate cake with raspberries.

Oppenheimer saw to it that Edith had access to as much chocolate, sugar and butter as she needed to make her cakes, even during wartime rationing. The little tea house served a greater purpose as a moral booster to the isolated scientists.

Warner was well known and well loved by Los Alamos. Several books have been written about her, including the 1960 biography by Peggy Pond Church titled The House At Otowi Bridge. Her story also fueled two stage plays and even an opera titled The Woman at Otowi Crossing and performed by the Opera Theater of Saint Louis in 1995.

The recipe was shared by the Los Alamos Historical Society and further adjusted by Patty Templeton, archivist at the National Security Research Center, to include temperatures which weren't a part of Edith's original wood-fired stove recipe.

Cake Icing
  • 2 eggs beaten
  • 1 cup granulated sugar
  • 2 1/3 cups flour (sifted 3 times)
  • 1/2 teaspoon salt
  • 2 teaspoons baking powder
  • 1 teaspoon vanilla
  • 1/2 cup milk
  • 1 1/2 ounces baker's chocolate
  • 4 tablespoons butter
  • 3 heaping tablespoons cocoa
  • 1 1/2 cups powdered sugar
  • 1/2 teaspoon vanilla
  • 2 tablespoons melted butter
  • 2 tablespoons coffee or milk

Preheat oven to 250ºF. Grease and flour a 9-inch by 5-inch loaf pan. Mix eggs, sugar and flour. Gradually mix in milk, then salt, vanilla and baking powder. Melt baker's chocolate and butter then beat with remaining ingredients until light.

Bake for 15 minutes at 250ºF, then increase to 275ºF for 15 minutes, then 300ºF for a total of 1 hour bake time.

Prepare icing by sifting sugar and cocoa together, then beating all ingredients until smooth. Top with fresh raspberries.

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