• Preheat oven to 350F. Line 24 wells of muffin pans with paper cupcake liners; set aside.
• In a medium mixing bowl, whisk together the cocoa powder, baking soda, and salt.
• Carefully add the boiling water and whisk until well blended. Set the mixture aside.
• In a large mixing bowl, combine the sugar, melted butter, vegetable oil, and vanilla.
• Using an electric mixer or a whisk, beat in the eggs and egg yolks one at a time, just until combined.
• Add the cocoa mixture and the milk, stirring just until combined.
• Add the flour and stir the batter with a wooden spoon or spatula, just until the flour is incorporated.
• Scoop the batter into the prepared muffin pans, filling each well to about 2/3 full.
• Bake the cupcakes at 350F for 18-20 minutes until a toothpick inserted into the center comes out clean.
• Cool the cupcakes in the pan for 5 minutes, then transfer to a wire cooling rack to cool completely to room temperature.

Frosting Directions:

• In a large mixing bowl, use an electric mixer to beat the butter until smooth and creamy.
• Add the unsweetened cocoa powder, milk, and vanilla extract, then beat until well incorporated.
• Mix in the powdered sugar about ½ cup at a time until you reach your desired consistency.
• Spread or pipe the frosting onto the room completely cooled cupcakes.