Chocolate Cake with Chocolate Buttercream

Its my cousin's birthday and every year my aunt calls me to make him a cake.  He loves chocolate so I search for a new super chocolaty recipe every year.  This year wins!  This cake is so moist and very rich!  I feel like I am cheating using a box mix, but of all the chocolate cake recipes I have tried, the box mix is always better and never disappoints.  Chocolate buttercream has been a challenge too.  I have found that most recipes are not very fudgey or are too sweet.  This recipe was perfectly chocolaty and a great consistency for the cake.  So stop your endless chocolate cake search like I have and try this recipe!  The best part is its super EASY!

It says "Happy Birthday" but its kinda hard to read...

Chocolate Cake - Adapted from kevinandamanda.com
1 Box Devils Food Cake Mix
1 4oz Box of Instant Chocolate Pudding
1 Cup Sour Cream
4 Eggs
1/2 Cup Canola Oil
1/2 Cup Water or Milk
For additional chocolate you can add chocolate chips to the batter

Chocolate Buttercream
1 Cup (2 Sticks) Butter, Unsalted and Room temp
5 1/2 Cups Powdered Sugar
1 1/2 Cup Unsweetened Cocoa Powder, sifted
1 Teaspoon Vanilla
2/3 Cup Milk

Directions:

1. For the cake, follow directions on box but with the listed ingredients.  Bake according to the box.  I did 2 - 8in pans and it was about 30 minutes each.
2. For the buttercream, cream the butter with the whisk attachment of your kitchen aid until light and fluffy.  Alternate adding the wet ingredients and the dry until everything is in the bowl.  Whip up until desired consistency, add more milk if needed.  
3. Frost you cake, and ENJOY!