Spray three 9” (23 cm) cake pans with cooking spray for baking.
In a large heat safe bowl, add the 2 oz (56 g) of chocolate. Add the cocoa powder and then the hot boiling water, whisk to combine. Chocolate will melt as you whisk.
Add the sugar, whisk to combine. Then add the oil, whisk to combine. At this point the batter is cool enough to add the eggs without scrambling. Add eggs one at a time and whisk until smooth. Add the vanilla and set aside.
In a smaller bowl whisk together the flour, baking soda and salt. Add flour mixture in thirds to the chocolate mixture, stirring gently with a wire whisk until combined.
Pour batter into the pans. Filling each one 1/3 of the way full. Tap on counter to release air bubbles.
Bake for 22-25 mins, or until a long toothpick or skewer comes out clean.
Allow cakes to cool and then release them from the pans onto cooling racks.
To make frosting whip all ingredients (EXCEPT MILK) with an electric mixer on high speed until frosting forms soft but slightly stiff peaks. Then thin with milk ¼ cup at a time until desired consistency.
Transfer first layer to cake stand with a cake lifter or large spatula.
Dollop ¾ cup of frosting in the center and smooth with an offset spatula just to the edge.
Place second layer on top and repeat, and then third and final layer and repeat. Create nice swirls with the offsets spatula for a decorative finish.
Sprinkle top with gold sprinkles and top with birthday candles.