Flecked with vanilla seeds throughout the dough, alfajores are the perfect excuse to whip up a batch of vanilla bean cajeta—a goat's-milk variation on dulce de leche. The combination of gooey toffee sauce and buttery shortbread can't be beat, but it can be improved upon. My recipe replaces traditional cornstarch with tapioca starch, keeping the alfajores tender and light, with a clean finish that truly melts away. Pair them with a mug of strong black coffee, or a nip of Rainwater Madeira.
Why It Works
- Tapioca starch breaks down at relatively low temperatures, eliminating the starchy aftertaste associated with traditional cornstarch-based recipes.
- Powdered sugar dissolves more readily in a low-moisture dough, leaving no trace of grit.
- Egg yolks bind the dough while keeping the overall water content to a minimum, so the cookies are easy to roll yet tender after baking.
- Vanilla bean keeps the dough flavorful but dry, so it's easy to handle.
- A food processor minimizes aeration of the dough while keeping it nice and cold, so the dough doesn't need to be chilled and the cookies won't puff or warp with pockets of air.
- Yield:Makes 25 (2-inch) sandwich cookies
- Active time: 25 minutes
- Total time:45 minutes
- 1 vanilla bean, preferably Mexican
- 4 ounces all-purpose flour (3/4 cup plus 1 tablespoon; 115g)
- 3 ounces tapioca starch (3/4 cup; 85g)
- 2 ounces powdered sugar (1/2 cup; 55g), plus more for dusting
- 1/4 teaspoon (1g) Diamond Crystal kosher salt
- 1/4 teaspoon (1g) baking powder
- 4 ounces cold unsalted butter (1 stick; 115g), cut into 1/4-inch pieces
- 2 large egg yolks, cold
- 1 recipe Cajeta Casera (see note)
Split vanilla bean lengthwise with a paring knife and scrape out seeds with the flat of the blade; reserve empty pod for cajeta or another use. Combine vanilla seeds with flour, tapioca starch, powdered sugar, salt, baking powder, and butter in the bowl of a food processor. Pulse to form a fine and sandy meal, then add egg yolks and continue processing until the dough balls up around the blade. Divide in half and proceed to step 2, or wrap tightly in plastic and refrigerate up to 1 week.
Adjust oven rack to middle position and preheat to 350°F (180°C). Turn a portion of dough onto a powdered sugar–dusted surface and dust more powdered sugar on top. Roll dough until roughly 6 inches across, then dust with powdered sugar, flip upside down, and dust again. Continue rolling until dough is just shy of 1/4 inch thick. Slide a thin offset spatula under dough to loosen any places that might have stuck and cut dough into 2-inch rounds. Arrange cutouts on a parchment-lined aluminum half-sheet pan, leaving about 1/2 inch between cookies. Gather the scraps, briefly knead, and re-roll and cut as before. Repeat with remaining dough, for a total of 50 pieces. Bake until just beginning to brown around the edges, about 15 minutes, and cool to room temperature directly on sheet pan.
Transfer cajeta to a pastry bag fitted with a plain 1/4-inch tip. Flip half the cookies bottom side up and pipe a generous dollop of cajeta into the very center, up to 1/2 ounce (4 teaspoons; 14g), or less if you prefer. Alternatively, this can be done with a spoon. Top with remaining wafers and press gently to secure. Dust with powdered sugar and serve. In an airtight container, alfajores will keep 24 hours at room temperature or up to 1 week in the fridge.