Preheat oven to 350 Degrees F.

Grease a 9 X 12-inch baking pan, and line it with parchment paper. Let the paper overhang at least 2 inches on all sides. Grease the paper inside the pan.

In a separate bowl whisk together the all-purpose flour, baking powder, lebkuchen or gingerbread spices, espresso powder, and salt. Set aside.

Melt the semi-sweet chocolate chips and the unsalted butter together over a double boiler.

Whisk in the white granulated sugar, pure vanilla extract, and, if desired, the bourbon.

Once the sugar dissolves, remove the mixture from heat and let the mixture cool completely.

Crack the eggs into a separate bowl and lightly beat them with a fork.

Add the beaten eggs to the cooled butter, chocolate, and sugar mixture and whisk briskly until the eggs have been completely combined into the batter.

Fold the mixture into the dry ingredients and scrape the brownie batter into the prepared pan.

Bake for 45 minutes or until a knife inserted into the center of the pan comes out clean.

Remove from oven, let stand in the pan for 15 minutes, then use the overlapping parchment paper to transfer the uncut brownies to a wire rack.

Let the brownies cool completely before frosting.

In a small bowl, whisk together the lebkuchen or gingerbread spice mix with the espresso powder and a pinch of salt.

Place the unsalted butter and unsweetened cocoa powder in a mixer, and beat until combined. Add the pure vanilla extract and the heavy cream.

Stop the mixer and add the powdered sugar. Turn the mixer on the lowest speed and mix until the powdered sugar is completely incorporated into the frosting.

If the frosting is too thick for your liking, add some more heavy cream a teaspoon at a time until you achieve the desired consistency. If the frosting is too thin, add more powdered sugar to stiffen it a bit.

Use a pastry knife to spread the frosting over the brownies.

Cut into squares, plate, and serve.