Preheat your oven to 350°F (175°C) and line your cupcake tins with paper liners. This gives you a solid base to bake your cupcakes.
In a large mixing bowl, combine 1⅓ cups of flour, 2 cups of sugar, 1 cup of cocoa, 1½ teaspoons of baking soda, 1½ teaspoons of baking powder, and 1 teaspoon of salt. Whisk them together until well blended, ensuring no clumps remain.
In a separate bowl, crack 2 eggs and add 1 cup of whole milk, ½ cup of oil, and 2 teaspoons of vanilla. Beat these together until the mixture is smooth and well combined.
Pour the wet ingredients into the bowl with the dry ingredients. Mix everything together until fully incorporated. The batter should be smooth and slightly thick.
Beat the mixture on medium speed for about 3 minutes. This introduces air into the batter, helping the cupcakes rise beautifully.
Slowly add 1 cup of boiling water to the batter, starting with just a small amount. This step is crucial as it enhances the chocolate flavor. Mix well until combined; the batter will be quite runny.
Scoop the batter into the lined cupcake cups, filling them about ¾ of the way full. Make sure not to overfill; this will allow them to rise without spilling over.
Place the cupcake trays into the preheated oven and bake for 20 to 25 minutes. You know they’re ready when a toothpick inserted into the center comes out clean.
Once baked, remove the cupcakes from the oven and let them cool in the tins for about 10 minutes. Then, transfer them to a wire rack to cool completely.
While they cool, prepare the frosting. In a bowl, cream together 1 cup of unsalted butter and 4 cups of powdered sugar until it’s light and fluffy. If it seems too thick, add a few drops of heavy whipping cream until it reaches your desired consistency.
To check if the frosting can hold a stiff peak, take a spoonful of it and turn the spoon upside down. If it stays put, you’re good to go! If not, add more powdered sugar, half a cup at a time, mixing well.
Once the frosting is ready, scoop it into a pastry bag fitted with a large star tip. This will help you create those iconic swirls on each cupcake.
Frost the cooled cupcakes by holding the bag straight up and down. This will give you that classic look.
Finally, place 2 large candy eyes on top of each frosted cupcake. Cut the chocolate chip cookie in half and stick it into the frosting to mimic Cookie Monster’s mouth. Enjoy the delightful chaos of making these fun cupcakes!