For the Cupcakes:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with cupcake liners.

2. Mix Dry Ingredients: In a large bowl, sift together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.

3. Add Wet Ingredients: Add the eggs, milk, oil, and vanilla extract to the dry ingredients. Mix until well combined.

4. Add Boiling Water: Slowly stir in the boiling water. The batter will be thin, but that’s okay—this makes the cupcakes extra moist.

5. Fill the Cups: Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

6. Bake: Bake for 18-20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.

7. Cool: Let the cupcakes cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.

For the Chocolate Frosting:

1. Make the Frosting: In a medium bowl, beat the softened butter and cocoa powder together until smooth.

2. Add Powdered Sugar and Milk: Gradually add the powdered sugar, one cup at a time, alternating with the milk. Beat well after each addition.

3. Add Vanilla and Salt: Stir in the vanilla extract and salt. Beat the frosting until it’s smooth and fluffy. If the frosting is too thick, add a little more milk to reach your desired consistency.

4. Frost the Cupcakes: Once the cupcakes are completely cool, frost them with the chocolate frosting using a spatula or piping bag.