In a medium-sized bowl, cream butter and sugar. Add eggs one at a time, beating well after each addition. Mix in vanilla.
In a large bowl, sift flour with baking powder; add salt. Combine flour mixture with egg mixture; mix well. Slowly add evaporated and whole milk; mix well.
Pour batter into a greased 8x8 pan and bake in at 350°F (180°C) for 35 minutes or until golden. Set aside to cool, then cut the cake into 1 ½-inch squares.
Makes 24 servings