Instructions

1. In a food processor, pulse together the flour, sugar, cocoa powder and salt. Add the butter and vanilla and pule until the mixture just comes together.
2. Line an 8 x 8 inch pan with parchment paper. I used an 8 x 16 inch strip so that 2 sides were lines but the other two were not. Press the shortbread into the pan and prick generously with a fork.
3. Chill at least 30 minutes in the refrigerator.
4. Preheat the oven to 325°F. Bake the shortbread for 25 minutes until it is firm to the touch and just beginning to pull away from the sides.
5. While the shortbread cools, prepare the ganache. Heat the heavy cream until it almost boils. Remove from heat and add the chocolate. Wait a few minutes before stirring to give the chocolate a chance to melt.
6. Add the appropriate liqueur. Stir until smooth. If desired, mix in the appropriate add in.
7. Pour the ganach on top of the shortbread. Cool thoroughly.
8. If you used the 8 x 16 inch piece of parchment paper to line the pan, you will need to loosen the two unlined sides with a sharp knife. Then use the parchment paper to lift the bars out of the pan before cutting them. It's easier to cut them on a cutting board.