Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish and line it with parchment paper.

In a medium saucepan over low heat, melt the unsalted butter, stirring until smooth. Mix in granulated sugar and dark brown sugar until well combined.

Add the eggs one at a time, whisking after each addition. Stir in the vanilla extract.

In a separate bowl, sift together all-purpose flour, cocoa powder, ground ginger, cinnamon, cloves, nutmeg, salt, and baking powder.

Fold the dry ingredients into the butter and egg mixture until just combined.

Fold in molasses, chocolate chips, and chopped crystallized ginger until evenly distributed.

Pour the batter into the prepared baking dish, spreading it evenly.

Bake for 30–35 minutes, checking for doneness with a toothpick.

Allow the brownies to cool for 10 minutes, then transfer to a wire rack to cool completely before slicing.