Preheat oven to 180ºC (350ºF). Place the butter and sugar in an electric mixer and beat for 8–10 minutes or until pale and creamy. Add 1 tablespoon vanilla extract and beat to combine. Gradually add the eggs, one at a time, beating well after each addition. Gradually add the flour and beat until just combined. Spoon the mixture into a lightly greased 20cm x 30cm slice tin lined with non-stick baking paper and bake for 30–35 minutes or until cooked when tested with a skewer. Using a skewer, make holes all over the top of the cake and place in the refrigerator to cool completely.
While the cake is cooling, place the milk or evaporated milk*, condensed milk, buttermilk and remaining vanilla in a jug and mix well to combine. Pour the milk mixture over the cake and return to the refrigerator for a further 2 hours or until the milk mixture is absorbed. Best would be overnight.
Place the cream in a bowl and whisk until soft peaks form. Top the cake with the cream and serve.
Recipe by MADaboutkitchen at https://madaboutkitchen.in/tres-leches-3-milk-cake/