For the cupcakes

1. Line cupcake mold with liners. Preheat oven to 160 C (Reduce temp to 140 or 150 C if using convection oven)
2. Sift together flour, cocoa powder, baking powder, baking soda, salt, powdered sugar.
3. Add oil, vanilla extract yogurt, vanilla extract and water / milk.
4. Mix to form a smooth batter. If the batter is too thick, loosen up with some more milk or water.
5. Fill each cupcake mold upto half or three-fourth of the way with the batter.
6. Bake at 160 C for 20 minutes or until the cupcakes are fully cooked through. Prick the cupcakes with a toothpick. If it comes out without leaving any wet batter, it is done
7. Remove and let it cool completely. You can remove the cupcake liners if you want.

To make the Chocolate Buttercream Frosting

1. Melt the chocolate in microwave or using the double boiler method until it is fully melted. Mix it well and let it cool completely. Keep stirring consistently to avoid forming a skin or harden the chocolate.
2. Add butter at room temperature, vanilla extract and powdered sugar to a mixing bowl. Cream together for 2-3 minutes to form a smooth and creamy mixture (You can do it with a spatula , spoon or electric whisk.)
3. Add the cooled and melted chocolate to the buttercream and mix well. If it is warm and your buttercream is starting to melt a little, stick the bowl in the fridge for 10-15 minutes to thicken it up.

Frosting the cupcakes

1. Fill a ziplock bag or a pastry bag with the frosting and frost as much or as little as you want on each cupcake
2. You can also decorate with sprinkles, chocolate chips, chocolate shards etc.

Serve

1. Let the cupcakes chill in the refrigerator for 30 minutes at least before serving.
2. Store in an air tight box in the refrigerator for up to 3 days.