Set the oven to 350°F (175°C). Lightly coat an 8x8-inch baking pan with non-stick spray and line it with parchment paper.
Whisk together in a bowl, the flour, baking soda, baking powder, salt, ginger, cinnamon, and nutmeg.
Combine in a large mixing bowl, the softened butter and brown sugar. Use a hand mixer to blend until smooth. Mix in the eggs until well incorporated and then follow with the molasses, pumpkin purée, and vanilla.
Add the dry ingredients to the wet and mix gently until just combined (don’t overmix).
Pour into prepared pan and smooth the top. Bake for 30-35 minutes, or until a toothpick comes out clean.
Let cool for at least 15 minutes before slicing into snack-size squares. Enjoy as-is or top with a quick glaze.