Preheat oven to 375 degrees F (190 degrees C). Lightly butter, muffin cups with paper liners.
In a small bowl mix hot water and the cocoa powder. Let cool to room temperature.
In another bowl, whisk together the flour, baking powder, and salt.
Then in the bowl of your electric mixer, or with a hand mixer, beat the butter and sugar until light and fluffy. Add the eggs, one at a time, beating until smooth. Scrape down the sides of the bowl as needed. Beat in the vanilla extract. Add the flour mixture and beat only until everything mix properly. Then add the cooled cocoa mixture and stir for 5-10 minutes.Now Batter is ready.
Fill each muffin cup about two-thirds full with batter and bake for about 16 - 20 minutes or until risen, springy to the touch, and a toothpick inserted into a cupcake comes out clean.Remove from oven and place on a wire rack to cool. Once the cupcakes have completely cooled,you can decorate your cupcakes with icing.