To begin, preheat your oven to 180°C (350°F) and line a baking sheet with parchment paper. In a large bowl, cream the softened butter and sugar using a hand mixer or whisk until light and fluffy. This step ensures a delicate texture for the cookies. Add the egg yolk and vanilla extract, mixing until fully incorporated.

In a separate bowl, sift together the flour, corn starch, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, mixing with a spatula or your hands until a soft, smooth dough forms. Avoid overmixing, as this can toughen the cookies. If the dough is too sticky, chill it in the refrigerator for 15 minutes.

Lightly flour a clean work surface and roll out the dough to a thickness of about 5mm (¼ inch). Use a round cookie cutter (approximately 5cm/2 inches in diameter) to cut out circles. Place the circles on the prepared baking sheet, leaving a small gap between each.

Bake the cookies in the preheated oven for 10–12 minutes, or until they are just beginning to turn golden around the edges. Avoid overbaking, as alfajores are meant to be soft and delicate. Remove from the oven and let the cookies cool completely on a wire rack.

While the cookies cool, prepare the filling. Place the dulce de leche in a small bowl and stir to ensure it has a smooth, spreadable consistency. If you prefer a thicker filling, refrigerate the dulce de leche for 10–15 minutes.

Once the cookies are completely cooled, spread a generous layer of dulce de leche on the flat side of one cookie. Gently press another cookie on top to create a sandwich. Repeat until all the cookies are paired and filled.

If desired, roll the edges of the filled cookies in shredded coconut for a traditional touch. Alternatively, dust the tops with powdered sugar for a simple yet elegant finish. Ensure the edges are clean and the filling doesn’t overflow for a polished presentation.

Serve the alfajores with a cup of coffee or mate for an authentic Argentine experience. Arrange them on a platter with a light dusting of powdered sugar for an inviting look. Store any leftovers in an airtight container at room temperature for up to 3 days to preserve their texture and flavour.