Preheat oven to 175C (350F) and grease an 8x8 inch square baking pan.
In a large bowl, whisk together melted butter, granulated sugar, and molasses until well combined.
Add the egg and vanilla extract, whisking vigorously until the mixture is smooth and glossy.
Sift in the flour, cocoa powder, ground ginger, cinnamon, cloves, nutmeg, and salt.
Fold the dry ingredients into the wet mixture using a spatula until just combined; do not overmix.
Gently fold in the chocolate chips.
Spread the batter evenly into the prepared baking pan.
Bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow to cool completely in the pan before slicing into 16 squares.