Preheat your oven to 350°F (177°C) and prepare a 9x9-inch baking dish by lining it with parchment paper.

In a large mixing bowl, combine melted unsalted butter with light brown sugar. Stir until smooth and creamy, about 1-2 minutes. Add in the eggs, molasses, and vanilla extract, mixing until fully incorporated.

In a medium bowl, whisk together the all-purpose flour, ground ginger, cinnamon, baking powder, and kosher salt.

Gradually add the dry mixture to the wet ingredients, stirring gently until just combined.

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

Bake for 30-35 minutes until set edges and a center that no longer jiggles.

Once baked, cool in the pan for 15-20 minutes, then transfer to a wire rack to cool completely. Dust with confectioners' sugar.

Slice the cooled brownies into squares and serve as is or with a scoop of vanilla ice cream.