Preheat oven to 350ºF. Line a 12-cup muffing tin with cupcake liners.
In a large bowl, sift together sugar, flour, cocoa, baking powder, baking soda and salt.
In another bowl, mix with an electric mixer the eggs, buttermilk, vanilla, canola oil. Add water and mix until very smooth. The batter will seem very runny, but they will be fine.
Fill cupcake liners ¾ full and bake in preheated oven for 22-27 minutes. Allow to fully cool before filling. *if you don’t have any buttermilk, just use milk and add 2 tsp white vinegar; set aside for 5 minutes to curdle.