Preheat your oven to 350°F (175°C) and grease a 9x5 inch loaf pan or line it with parchment paper.
In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, nutmeg, ginger, and granulated sugar until well combined.
In another bowl, mix the pumpkin puree, milk, melted butter, egg, and vanilla extract. Stir until smooth and fully combined.
Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Be careful not to over-mix.
In a small bowl, combine the brown sugar and pumpkin pie spice.
Take a portion of the dough and divide it into several small pieces (about 1-2 inches each). Roll each piece into a ball.
In the prepared loaf pan, layer the dough balls, sprinkling the brown sugar and spice mixture between the layers. If using, add a few chopped walnuts between some layers for extra crunch.
Once all the dough balls are in the pan, sprinkle any remaining brown sugar mixture on top.
Bake in the preheated oven for 30-35 minutes or until the top is golden brown and a toothpick inserted comes out clean.
Allow the bread to cool in the pan for about 10 minutes before transferring to a wire rack to cool completely.
Notes
Serve warm, dusted with powdered sugar and drizzled with maple syrup.