In the bowl of a food processor fitted with the metal blade, pulse to combine the flours, cocoa powder, baking powder, baking soda and salt.
Add in the pieces of cold butter, pulsing the machine about 20-30 times until the butter is incorporated.
Stir the buttermilk and molasses together to completely mix the two. Slowly pour the liquid into the flour while pulsing the machine. Pulse just until the mixture comes together and holds together when pressed between your fingers. It will be crumbly.
Turn out onto a floured surface and bring together by kneading just lightly.
Pat or roll out to a disk about 8 inches round. Use a 2 1/2 inch biscuit cutter to cut out 7 or 8 biscuits. You will need to reform the dough once for the last one or two.
Set the biscuits on a silpat or parchment lined baking sheet and set in the refrigerator or freezer while you clean up. This will re-chill the butter for a better texture.
Bake for about 15 minutes until risen.
Brush with a little melted butter and sprinkle with caraway seeds.