To make the cake, combine your dry ingredients in a medium bowl (2 cups flour, 1 teaspoon baking soda, 1/2 teaspoon baking powder, 1/2 teaspoon salt, 2 teaspoons cinnamon, 1 1/2 teaspoons pumpkin spice).
Next, combine the 1 cup pumpkin puree, 1/2 cup light brown sugar, 1/2 cup melted coconut oil, 1/4 cup pure maple syrup (not maple pancake syrup), and 1/4 milk. Whisk till combined and then fold in the dry ingredient mixture until the batter is just combine, don't overmix.
The batter will be thick, this is normal. Spread batter evenly in your prepared baking pan.
Sprinkle streusel topping over cake batter and lightly press down.
Bake for 30-35 minutes, or until a toothpick comes out mostly clean, there will some crumbs from the topping but the cake should be done. Allow to cool while you are making the glaze.