Preheat oven to 350º. Lightly grease a muffin tin with cooking spray, or line with paper muffin liners.

Prepare streusel topping: In a small bowl, whisk together 4 tablespoons sugar, 1 tablespoon flour, and ½ teaspoon cinnamon. Add 2 teaspoons oil and mix together until you have a sandy texture; set aside.

In a mixing bowl, whisk together flour, baking powder, baking soda, salt, pumpkin pie spice, and cinnamon; set aside.

In a large mixing bowl, combine pumpkin, sugar and melted butter; add sour cream, eggs, and vanilla and beat at medium speed until well blended.

Add flour mixture and stir until just combined. Stir in cranberries.

Divide batter evenly into 12 muffin cups. Sprinkle muffins with streusel topping.

Bake at for 20 to 25 min, until a tester inserted into the center comes out clean.

When muffins are done, cool for a few minutes in the muffin pan before removing to cool on a wire rack.