Preheat oven to 350°F (175°C). Grease and flour two 9-inch round baking pans.
In a large bowl, cream together the sugar and butter until light and fluffy.
Beat in eggs one at a time, then stir in the vanilla.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients. Beat until just combined.
Pour batter into prepared pans and bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.
Let cakes cool in pans for 10 minutes before inverting onto wire racks to cool completely.
Make frosting: In a large bowl, beat butter until light and fluffy. Gradually add powdered sugar, beating until smooth.
Stir in evaporated milk, brown sugar, coconut, and vanilla.
Frost cooled cake layers and enjoy!
Notes
For a richer flavor, use dark brown sugar in the frosting. You can also add chopped pecans or walnuts to the cake batter.