Preheat and Prepare: Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with parchment paper for easy removal.
Mix Wet Ingredients: In a large mixing bowl, whisk together the melted butter, molasses, brown sugar, eggs, oil, milk, and vanilla extract.
Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, ginger, cinnamon, mixed spice, and salt.
Combine The Ingredients: Gradually add the dry ingredients to the wet ingredients in three additions. Mix until just combined; do not overmix.
Bake the Loaf: Pour the batter into the prepared loaf pan and smooth the top. Tap the pan to remove any large air bubbles. Bake for 55 minutes, or until a toothpick inserted into the center comes out clean.
Cool and Serve: Allow the loaf to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.