While crumb cake might be too ordinary for most to request on their birthday, it was the perfect choice for my frosting-loathing and spice-loving Astronomer. To up the celebratory quotient, I swapped out traditional cinnamon for a heaping teaspoon of Guatemalan cardamom—it’s the birthday boy’s current obsession.
I knew this America’s Test Kitchen recipe would yield a winning cake, but The Astronomer’s reaction was even better than expected. Don’t tell his mama, but he declared it to be “the best birthday cake ever!” Oh, how will I ever top this in the future?
Employing cake flour in both the crumb topping and cake resulted in a delicate body and a satisfying crumb. Rich buttery notes tied everything together, while the cardamom added a sexy touch like only it can.
Although I initially frowned upon The Astronomer’s desire for a such a pedestrian cake, this one made me a crumb cake convert, and I wouldn’t hesitate to request it for my next birthday. Mmm, cardamom!
For crumb topping
- 1/3 cup (2.3 ounces) granulated sugar
- 1/3 cup packed (2.3 ounces) dark brown sugar
- 1 teaspoon ground cardamom
- 1/8 teaspoon salt
- 8 tablespoons (1 stick) unsalted butter, melted and cooled
- 1 3/4 cups (7 ounces) cake flour
For cake
- 1 1/4 cups (5 ounces) cake flour
- 1/2 cup (3.5 ounces) granulated sugar
- 1/4 teaspoon baking soda
- 1/4 teaspoon salt
- 6 tablespoons (3/4 stick) unsalted butter, cut into 6 pieces and softened
- 1 large egg, room temperature
- 1 large egg yolk, room temperature
- 1 teaspoon vanilla extract
- 1/3 cup buttermilk, room temperature
- Confectioners’ sugar, for dusting
Make topping
Whisk the granulated and brown sugars, cardamom, salt, and melted butter together in a medium bowl to combine. Stir in the flour until the mixture resembles a thick, cohesive dough. Let the crumb topping mixture rest at room temperature until needed.
Make cake
Adjust an oven rack to the middle position and heat the oven to 325 degrees. Line an 8-inch square baking pan with a foil sling and grease the foil.
Whisk the flour, granulated sugar, baking soda, and salt together in a large bowl. Using an electric mixer on medium-low speed, beat the butter into the flour mixture, one piece at a time, about 30 seconds. Continue to beat the mixture until it resembles moist crumbs, 1 to 3 minutes.









