Found this recipe on Pinch of Yum and had to share. It may seem like alot of steps in this recipe, but it is well worth it, this is my go to recipe when Im hungry for a chocolate cake, and using the Ghiradelli chips make it so good!
With electric mixer, cream butter, sugars. Add the eggs and mix well.
Add flour, baking soda, salt, and cocoa and mix until just incorporated.
Add your 1 3/4 cup of boiling water to your oatmeal and let stand for a few minutes. Once oats are soft add oats and water mixture to the batter and mix well.
Stir in half of the bag of chocolate chips ( 6 ounces )
Pour into a greased 9x13 cake pan. Sprinkle the top of the cake with the rest of the bag of chocolate chips (6 ounces )
Bake at 350 for 30-40 minutes or until the surface springs back lightly when touched. (do not overbake ) let cool completely.
For the frosting: melt the 6 Tablespoons of butter,1 1/2 cups of sugar, and the 6 Tablespoons of milk in a large saucepan over med-low heat. Bring to a boil, and boil for 30 seconds.
Reduce heat to low and add a 1/2 - 3/4 cup of chocolate chips and 1/2 -3/4 cup of mini marshmallows. Stir or whisk until frosting is smooth. Pour immediately over the cooled cake. The frosting crystallizes almost immediately as it cools so its very important to get it on the cake while its still piping hot. Allow the frosted cake to cool for 5 minutes before serving.