500 g (1 lb. 2 oz) flour
400 g (14 oz) butter, at room temperature
100 g (3 1/2 oz) powdered sugar
Powdered sugar to sprinkle on top
Zest of 1 lime or orange
2 cans (14 ounces each) of condensed milk to make caramel for the filling
Put the 2 cans of condensed milk in a pan and cover with water. Boil for two hours (or only 45 minutes if you use a pressure cooker). Take out the cans and rinse with cold water. Let cool completely before opening the can. Use this caramel to fill the alfajor.
Mix the flour with the butter, powdered sugar and lemon zest. Knead until it forms a soft dough. Divide the dough into 3 equal parts. Roll out one of the parts on parchment paper, wax paper or a floured surface and cut a circle measuring 22-25 cm (11-12 inches). Place the circle (with the paper) on a greased baking sheet. Bake in a preheated oven at 350 °F (180 °C) for 15-20 minutes. Remove from the oven, and repeat the procedure with the two remaining dough portions. Once the three layers are ready, remove them from the paper. Place one layer on a round platter and spread it with caramel. Put a second layer on top and again spread with caramel. Cover with the third layer. Sprinkle powdered sugar on top.