Devil's Food Sheet Cake - Double Recipe
This recipe is like an old-fashioned mayonnaise cake, one that I have made many times because it is so good. When you are making the cake, it is hard not to snack and nibble. The mayo and the instant coffee are two unexpected ingredients that help make the cake wonderfully moist and chocolate-y.

YIELD: ABOUT 2000g (4# 6 oz) BATTER
TWO HALF SHEET PANS (13" x 18" x 1" / 33 cm x 45 cm x 2.5 cm) SCALED @ 1000g EACH



  • 400 grams pastry flour - King Arthur (3 cups)
  • 120 grams Dutch-process cocoa powder - Valrhona (1 cup + 3 Tablespoons)
  • 2 teaspoons baking soda (12g)
  • 1 tablespoon instant coffee - Medaglia D'Oro (3g)
  • ½ teaspoon fine sea salt (3g)

  • 200 grams eggs (4 large)
  • 20 grams egg yolk (1 large)
  • 500 grams granulated sugar (2½ cups)
  • 340 grams mayonnaise - Hellmann's (1½ cups)
  • 1½ teaspoons vanilla extract or vanilla bean paste

  • 420 grams water, room temperature (1¾ cups)

  • 2000 grams = Total 70 oz (4# 6 oz)

  • 225 grams bittersweet chocolate 60%, such as Ghiradelli - Two 4 oz (113g) bars

  1. PREP PANS: LINE two half sheet pans with Silpat mats. Spray with Pam (with flour) or Baker's Joy. Note: I like to use Silpat mats because they lie very flat, unlike parchment paper, which wrinkles when sprayed with non-stick spray. If you do use parchment, spray just before filling the pans, not ahead of time.
  2. PRE-HEAT OVEN TO 325° F (165° C).
  3. SIFT flour, cocoa, baking soda, instant coffee, and salt. Whisk to blend.
  4. MIX eggs and egg yolk on medium speed in Kitchen Aid (or other stand mixer), using the whisk, until combined. Gradually drizzle in the sugar with mixer running; turn speed to high and continue to whip until thick and pale in color, about 10 minutes.
  5. TURN speed to low and add mayonnaise, a spoonful at a time, with mixer running. Add vanilla.
  6. ADD ⅓ of the flour and pulse in gently on lowest speed.
  7. ADD ½ of the water and mix in.
  8. REPEAT with another ⅓ of the flour and ½ of the water.
  9. FINISH by adding the remaining ⅓ of the flour and mix just until all the flour is incorporated.
  10. STOP the mixer and scrape down sides and bottom of bowl and mix in. The batter will be very thin.
  11. SCALE two portions of batter (1000g - 2# 3 oz each) and spread evenly in pans with offset spatula. This will produce finished sheet cakes about ⅝" (1.5 cm) thick.
  12. BAKE @ 325° F (165° C) 25 - 27 minutes, until a wooden skewer tests clean, and the cake is just starting to pull away from the sides of the pans.
  13. LET COOL in the pans.
  14. FREEZE cakes in the pans.
  15. INVERT sheet cakes and spread a thin layer of melted chocolate on the bottom of the cake - 4 oz (113g) per sheet. Although this is an optional step, it is a professional technique that gives a nice finish to the layers, especially the bottom layer of a cake. I almost always do this.
  16. CUT the frozen cake into 6" (15 cm) rounds, 4 per half sheet pan (8 total). Use a cake board or 6" cake pan (or the removable bottom of a 6" cake pan) as a template for cutting the rounds.
  17. STACK the rounds (in two stacks of 4) as you cut them, layering with parchment paper.
  18. FOR CAKE CRUMBS: CUT all the cake scraps in cubes, spread on half sheet pans, and dry in a low oven 175° F (79° C) for 1 hour. Let cool. Process in food processor to fine crumbs.
Recipe Ancestry Notes:
Recipe adapted from Bouchon Bakery Cookbook by Thomas Keller with Sebastien Rouxel (2012). If you don't know about this cookbook, I highly recommend it.