Preheat the oven to 350 degrees.
Spray a Jumbo Muffin Pan with nonstick spray.
In a large bowl, whisk together the flour, baking soda, spices and salt. Set aside.
In another bowl, whisk together the oil, sour cream, buttermilk and sugars. Add in the eggs and whisk again, but be sure to not over mix.
Dump the dry ingredients, and pumpkin on the wet ingredients and switching to a rubber spatula or wooden spoon, gently fold the ingredients together just until a few streaks of flour remain.
Fill jumbo cupcake liners in a jumbo pan ⅔ full of batter. Or use a regular muffin tin.
Sprinkle the crumb mixture all over the top of the muffins.
Bake for 23-28 minutes and then remove from the oven to cool completely.
Sprinkle the tops with powdered sugar and serve.
Stir together the crumb mixture in a small bowl and set aside.
