Preheat oven to 350°.
Begin by prepping the frosting, Add the chocolate chips and butter to a medium microwave-safe bowl. Microwave for one minute and stir. Continue microwaving in 30 second increments, stirring well after each increment, until the chocolate chips are just melted. Place the bowl in the refrigerator to cool.
In a large bowl, whisk the eggs, buttermilk, oil, vanilla and sugar. Add the dry ingredients and stir until well combined. Mix in the chocolate chips.
Pour the batter into a greased 9x13 pan. Bake at 350° for 45-55 minutes, or until a toothpick inserted in the center comes out clean. Cool to room temperature.
Meanwhile, when the chocolate and butter mixture for the frosting is cooled enough to be solidified (roughly 2 hours), beat it with a hand mixer until light and fluffy. Add the powdered sugar and milk and beat until smooth with a good spreadable consistency..
Frost the cake with the buttercream and top with the chocolate shavings. Enjoy!