Preheat oven to 350°F (175°C) and grease an 8x8 inch baking pan with butter or parchment paper.

In a large bowl, whisk together melted butter, brown sugar, and molasses until well combined.

Add the egg and vanilla extract, whisking until the mixture is smooth and glossy.

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

Gradually fold the dry ingredients into the wet ingredients using a spatula until no streaks of flour remain.

Fold in the chocolate chips.

Transfer the batter to the prepared pan and smooth the top with a spatula.

Bake for 22 to 25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.

Remove from the oven and allow to cool completely in the pan on a wire rack before cutting into 16 squares.