Line your cupcake pans with liners and set aside (I made 24 minis & 10 full size).
Preheat oven to 350 degrees.
In a large bowl, mix together the flour, cocoa powder, sugar, baking soda, baking powder and salt with a whisk.
Add the eggs, oil, vanilla and milk and mix until combined. It will be very thick at this point.
I switched to a wooden spoon and added the hot water. Mix until fully incorporated. Now batter will be thin.
Fill the liners about 3/4 full and bake for full size – 12-15 minutes, minis – around 10 minutes until a toothpick inserted in the center comes out clean.
Cool completely before you start decorating.
For the Buttercream
Make sure you start with softened butter. I used my stand mixer but a hand mixer will work fine, too.
With the paddle attachment, whip the butter until it starts to get smooth.
Add the powdered sugar, one cup at a time, on medium speed for 1 to 2 minutes.
Add the heavy cream and vanilla extract and mix on high for 3 to 4 minutes.
If you use UNsalted butter, you’ll want to add a pinch of salt. I started with salted butter so there’s no need.
For the Decorating
Once cooled, core out the center of your cupcakes (if you want to fill them with buttercream). I used some type of apple corer to do this (I’m not sure exactly what it’s intended use is, I just found it in my drawer).
Using a piping bag (or ziploc bag with a tip), fill the center with some frosting then replace the top. Frost with the buttercream. It doesn’t have to be particularly pretty, you’re going to cover it up with sprinkles anyway.
Fill a bowl with the sanding sugar, flip the cupcake over and gently smush into the sprinkles to fully coat.
Cut some vanilla wafers in half for the ears (gently! this part is tricky. they were shooting all over when I was cutting them) and stick on each side of the cupcake.
Add a whole vanilla wafer for the mouth and use gel icing (or melted chocolate) to draw on the mouth & nose. I gave mine different faces & personalities.
I bought pre-made eyeballs, but I didn’t like them, so I flipped them over and drew on my own pupils with the icing.
Sources: Slight modifications to chocolate cupcakes (Bakerella) & buttercream (Sally's Baking Addiction)Makes: 24 mini & 10 full size cupcakes with enough frosting to fill half & frost all (I only turned the full size cupcakes into monkeys)