Baking this cake offers a sweet lesson in science
One of the great pleasures of baking is coming across a recipe you’ve never tried, giving it a shot and being really pleased with the results.
This is a recipe I found in a cookbook of interior Mexican cuisine and is called the Impossible Cake. It features the improbable reversal of cake and custard as the cake bakes in the hot oven.
There’s culinary wizardry going on here. A cake pan gets coated with the Mexican caramel called cajeta, spread with chocolate cake batter, topped with liquidy custard and slid into the oven, whereupon the batter starts puffing and rising through the liquid, not-yet-set custard. It eventually solidifies on top of the set custard or flan. A very tasty science lesson, I must say.
Impossible Cake

Photo by Jennifer Reynolds
INGREDIENTS
For the cake:
1 stick, plus 2 tablespoons softened butter
1 cup sugar
1 egg
2 tablespoons espresso powder dissolved in 11⁄2 tablespoons hot water
3⁄4 cup all-purpose flour
1 cup cake flour
3⁄4 teaspoon baking powder
3⁄4 teaspoon baking soda
1⁄3 cup plus one tablespoon cocoa powder (not Dutch processed)
1 cup plus, 2 tablespoons buttermilk
For the flan:
1 (12-ounce) can evaporated milk
1 (14-ounce) can sweetened condensed milk
4 eggs
1 teaspoon vanilla extract
For the topping:
1 cup cajeta, which is goat milk caramel. (Coronado brand Cajeta Envinada is available at most grocery stores.)
DIRECTIONS
Butter and flour a 10-inch-by-3-inch cake pan. (No spring forms, they’ll leak).
Pour cajeta into bottom of the pan. Tilt to coat the bottom.
For the cake: With flat beater on your electric mixer, beat the butter and sugar on medium-high until light in color and texture. Beat in eggs and espresso.
Sift the two flours together with the baking powder, soda and cocoa.
With the mixer on medium-low, beat in half the flour mixture, followed by half the buttermilk, repeat with the rest. Scrape down bowl and beat at medium-high for 1 minute.
To make the flan: In a blender, combine the two milks, eggs and vanilla. Blend until smooth.
Layer and bake: Scrape the cake batter into the prepared pan and spread level. Slowly pour the flan mixture over the cake batter. Better yet, use a ladle to ease the liquid on top of the batter. While you do this, set some water to a simmer.
Place the cake pan into a larger roasting pan and set on rack positioned in the middle of the oven set for 350 F. Pour your very hot water into the roasting pan until it comes up the side of the cake pan about 1 inch.
Carefully slide into the oven and bake 50-55 minutes, until a toothpick inserted in the center comes out dry. Remove from the water bath and set on a rack to cool for an hour. For easiest unmolding, refrigerate for a few hours or overnight.
To serve: Carefully run a thin-bladed knife around the edge of the cake/flan. Place a rimmed serving dish over pan and invert, jiggling several times to make sure the cake and flan drop.
Remove pan and scrape any remaining cajeta onto the cake.
Phil Newton is a Galveston baker/cook. He’s the owner/operator of Stiglich Corner with partner Cindy Roberts.
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