Preheat your oven to 350 degrees Fahrenheit, and line a 9x9 square baking dish with parchment.
In a medium mixing bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, nutmeg, and ginger.
In a separate bowl, whisk together the pumpkin puree, brown sugar, vegetable oil, maple syrup, and milk.
Add half of the flour mixture, and fold in.
Add the remaining flour mixture, and fold until just combined, careful not to over mix.
Spread the dough into the baking pan, and smooth out evenly.
In a medium mixing bowl, use a fork to stir together the flour, brown sugar, cinnamon, and butter for the crumb topping. It should be a crumbly mixture.
Sprinkle this over top of the batter.
Bake for 30-35 minutes, until a toothpick inserted in the center comes out clean.
If desired, whisk together the confectioner's sugar and milk and top the coffee cake with icing.