In a large bowl add butter, sugar, and mix until light and fluffy. Add egg, vanilla, and beat until well incorporated.
In a medium sized bowl add all purpose flour, baking powder, cocoa powder, and mix. Gradually add dry ingredients into wet ingredients until well incorporated.
Divide dough in half and wrap in plastic and refrigerate for at least 30 minutes
Preheat oven to 350F
Remove dough from fridge, using parchment paper below and above the dough roll out with a rolling pin.
Cut using heart shaped cutters and place on a greased baking pan and bake for 12 minutes.
To make the filling add ½ cup butter, half and half, pinch of salt and cream until light and fluffy. Gradually add powdered sugar.
With a start tip pipe the filling onto the cookie and place another cookie on top to make an Oreo Cookie