Preheat oven to 350 degrees and grease an 8 x 8 baking pan.
In a mixing bowl, combine the butter, brown sugar, pumpkin, and eggs using an electric mixer.
Add in the flour, baking powder, salt, cinnamon, ginger, allspice, and nutmeg.
Once all is just combined, pour into prepared pan.
In a separate bowl, prepare the topping by combining the flour, sugar, brown sugar, cinnamon, and melted butter using your hands or two forks.
Once crumbly, sprinkle over batter evenly.
Bake in the oven for about 45 minutes, or until toothpick comes out clean when inserted in center.
To prepare glaze, melt the butter in a saucepan.
Add in the powdered sugar, vanilla extract, and maple syrup.
Drizzle glaze on top of cake and serve!! Enjoy!