Preheat the oven to 350°F (175°C). Grease and flour a rectangular baking dish. In a medium bowl, whisk together the flour, baking powder, and cardamom powder. In a large bowl, cream the butter and sugar together until light and fluffy. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Step 2: Combine Ingredients

Gradually add the flour mixture to the butter mixture, alternating with the milk. Mix until just combined. Pour the batter into the prepared baking dish and smooth the top.

Step 3: Bake the Cake

Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean. Allow the cake to cool completely in the pan.

Step 4: Prepare the Tres Leches Mixture

In a bowl, combine the whole milk, sweetened condensed milk, and evaporated milk. Once the cake has cooled, poke holes all over the top with a fork and slowly pour the tres leches mixture over the cake, allowing it to soak in.

Step 5: Chill the Cake

Cover the cake and refrigerate for at least 4 hours, preferably overnight, to allow the flavors to meld.