01 - Preheat the oven to 350°F (175°C). Line an 8-inch square baking pan with parchment paper, leaving overhang for easy removal.
02 - In a medium bowl, whisk together the flour, baking powder, baking soda, salt, ground ginger, and cinnamon.
03 - In a large bowl, whisk the melted butter and brown sugar until well combined.
04 - Add eggs, one at a time, whisking thoroughly after each addition.
05 - Stir in the grated fresh ginger and vanilla extract.
06 - Add the dry ingredients to the wet mixture and gently stir until just combined.
07 - Pour in the milk and mix until smooth, taking care not to overmix.
08 - Spread the batter evenly into the prepared baking pan.
09 - Sprinkle crystallized ginger on top if desired.
10 - Bake for 28 to 32 minutes, or until a toothpick inserted into the center comes out clean.
11 - Allow bars to cool completely in the pan, then lift out using the parchment overhang and cut into 16 portions.