Step 1

Bake cake in a 13x9 inch pan according to the box directions.

Step 2

While cake is baking, whisk pudding and whole milk. Let stand for 2-3 minutes or until thickened. Then, whisk in sweetened condensed milk.

Step 3

When cake is done baking, poke holes in it using the handle of a wooden spoon.

Step 4

Pour pudding mixture evenly over the cake. Cool cake completely.

Step 5

In a large bowl, cream butter until light and fluffy. Stir in cocoa powder.

Step 6

Pour in boiling water, and vanilla. Mix until well combined.

Step 7

Gradually add in powdered sugar a little at a time until you reach your desired consistency.

Step 8

Evenly spread frosting over cake. Store in the refrigerator.