Preheat your oven to 350°F (175°C) and grease a 9-inch square baking pan.

In a large bowl, whisk together the dry ingredients: flour, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt.

In a separate bowl, whisk together the wet ingredients: pumpkin puree, eggs, vegetable oil, brown sugar, and granulated sugar until smooth.

Fold the wet ingredients into the dry ingredients until just combined, being careful not to overmix.

In a medium bowl, combine cold butter, flour, and sugar for the crumble topping and mix until it resembles coarse crumbs.

Pour the batter into the baking pan and sprinkle the crumble topping evenly over it. Bake for 25-30 minutes.

Let the cake cool in the pan for 10 minutes before transferring it to a wire rack and slicing into squares.