Ligia Rossi, who grew up in Costa Rica, is a fan of alfajores, soft and melt-in-your-mouth sandwich cookies filled with dense, creamy, caramel-y dulce de leche. These alfajores are tender thanks to the egg yolks, butter and cornstarch. Make an easy dulce de leche filling and pipe it between two cookies. The cookies are done when they’re still pale but set, and the bottoms are lightly golden. The baking time is key for a delicate cookie.
Note: Rossi makes a triple batch of these cookies; to scale up, multiply the measurements by three and instead of 2 egg yolks, use 1 whole egg plus 4 yolks. Make as many cans of dulce de leche as desired. You can store an unopened can of dulce de leche (it should have no dents or bulges) for several months. Or use it for ice cream, brownies, pancakes, churros — or eat it straight with a spoon.
