Preheat oven to 350º F. Grease and dust with flour a 9 x 13 inch cake pan.
Mix the cocoa with boiling water in small bowl, stir until smooth. Set aside to cool.
In a medium bowl, whisk together flour, baking soda, and salt. Set aside.
Using an electric mixer, beat butter and granulated sugar until fluffy.
Add the eggs, one at a time, beating well after each.
Stir in the vanilla extract.
Gradually add the cocoa mixture, beating well.
Gradually add the flour mixture into the butter mixture, alternating with the milk and sour cream. Mix until blended.
Pour batter into prepared pan.
Bake for 30-40 minutes or until wooden toothpick inserted in center comes out clean.
Cool completely. This recipe will make approximately 50 Cake Pops.