The cake is very popular in many parts of Central America and Mexico. The origins of the tres leches are disputed . The Nestlé Company also claims to have helped the tres leches recipe evolve, during World War II. The idea for creating a cake soaked in a liquid is probably of European origin, as similar cakes, such as rum cake from Puerto Rico and tiramisu from Italy, use this method.
A Tres leches cake, or Pastel Tres leches (Spanish, “Three milk cake”), or Pan Tres Leches (Spanish, “Three milk bread”), is a sponge cake—in some recipes, a butter cake—soaked in three kinds of milk: evaporated milk, condensed milk, and heavy cream. When butter is not used, the tres leches is a very light cake, with many air bubbles. This distinct texture is why it does not have a soggy consistency, despite being soaked in a mixture of three types of milk.-Wikepedia
See Recipe for Tres Leches from Foodpinup.com