Add the sifted cocoa powder to a medium sized bowl and pour in the cup of hot liquid. Whisk until completely dissolved.
Next add the buttermilk to cool down the mixture, then add the sugar and whisk until all is combined.
Add the eggs, oil and vanilla and mix again.
In a small bowl, stir flour, baking powder, baking soda and salt. Whisk this into the wet mixture until you no longer see any lumps.
Stir in heavy cream until evenly mixed in.
Lastly, stir in finely crushed Oreos.
Pour into cupcake tins and bake at 350 degrees F for 18-22 minutes or until done. Let cool and chill in fridge for at least 30 minutes.