Preheat the oven to 350 F. Spray a 9x13 pan with non-stick baking spray.
baking spray
Use a fork, whisk, or your hands to stir together the streusel ingredients in a small bowl until thoroughly combined. Place in the refrigerator while you make the coffee cake batter.
½ cup butter, 1 cup all-purpose flour, ½ cup brown sugar, ¼ teaspoon cinnamon
In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, cloves, all spice, granulated sugar, and brown sugar.
3 cups all-purpose flour, 1 ½ teaspoon baking powder, ¾ teaspoon baking soda, ¾ teaspoon kosher salt, 1 ¼ teaspoon cinnamon, 1 ¼ teaspoon ground ginger, ¾ teaspoon nutmeg, ½ teaspoon cloves, ½ teaspoon allspice, ¾ cup granulated sugar, ¾ cup brown sugar
In a separate bowl, whisk together the pumpkin, oil, sour cream and eggs.
1 15 oz can of pumpkin puree (about 1.5 cups), ¾ cup canola or neutral oil, ⅔ cup sour cream, 3 eggs
Pour the wet ingredients into the dry ingredients and mix with a rubber spatula until just combined, being sure to scrape the sides and bottom of the bowl as you go.
Pour the batter into the prepared pan and smooth into an even layer. Remove the streusel topping from the fridge and use a fork to break it up until it has a mix of small and medium crumbles. Sprinkle the streusel evenly across the top.
Bake for 40-45 minutes, or until a toothpick inserted in the middle comes out clean or with only a few moist crumbs. Cool at room temperature, then serve with a dusting of powdered sugar.
Powdered sugar: optional for dusting