Preheat your oven to 350 degrees F. and line a muffin tin with cupcake liners.
In a medium-sized bowl, sift together flour, cocoa powder, baking powder, baking soda, and salt.
Heat ½ cup water in the microwave until boiling. Add the chocolate chips to the hot water to melt. Set aside to slightly cool the mixture.
In a large bowl, add sugar, egg, and vegetable oil and beat with a hand mixer or a whisk until smooth.
Add vanilla extract and sour cream and mix.
Slowly add the cooled chocolate to the sugar mixture while mixing.
Add half of the flour mixture with half of the buttermilk and stir by hand. Once combined add the remaining flour and buttermilk and continue to stir until just combined. The batter will be thin and a bit lumpy. Line the cupcake tin with liners.
Divide the batter into the cupcake tin making sure to fill about 2/3 full so that the cupcakes do not rise past the cupcake liner. This is enough for approximately 14 cupcakes.
Bake the cupcakes for 16-17 minutes, or until a toothpick comes out clean.
Allow the cupcakes to cool completely then frost them with chocolate buttercream.