Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan.

Melt semisweet chocolate and unsalted butter in a medium saucepan over low heat, stirring until smooth.

In a large mixing bowl, whisk together flour, cocoa powder, baking powder, baking soda, cinnamon, ginger, nutmeg, cloves, and salt.

In a separate bowl, beat the eggs and brown sugar until light and fluffy, then mix in molasses and vanilla.

Slowly pour the cooled chocolate mixture into the egg mixture, stirring gently, then gradually add the dry mix, folding until just combined.

Fold in crystallized ginger and pour the batter into the prepared pan.

Bake for 25-30 minutes, or until a toothpick comes out with moist crumbs.

While cooling, whip up the frosting by beating cream cheese until smooth, then gradually mix in powdered sugar and eggnog.

Once brownies are cool, spread the Eggnog Frosting evenly over the top.

Let the frosted brownies sit for at least an hour for maximum flavor.