Preheat oven 350°F. Line a muffin or cupcake pan with paper liners and lightly spray them with cooking spray.
In a mixing bowl, combine all purpose flour, sugar, baking soda, espresso powder and salt. Mix well and set aside.
Melt butter and cool for a few minutes. Then stir in cocoa powder and hot water. Mix until smooth.
In a measuring cup, combine buttermilk, egg (replacer mixture) and vanilla extract.
Add the cocoa mixture and the buttermilk mixture to the flour and mix until combined.
Pour about ¼ cup of batter into each cup. Bake for 23~25 minutes or until a toothpick inserted into the center of a cupcake comes out clean. Remove from the oven and cool on a rack.