Pre-heat over to 350 degrees F. In a medium bowl add the pumpkin puree, egg, brown sugar, oil, milk, and vanilla extract. Stir until combined and smooth.
Add all the dry ingredients: flour, baking soda, baking powder, cinnamon, pumpkin pie spice, and salt. Stir just until the flour is mixed in.
Make the pepita streusel by stirring together the pepitas, brown sugar, flour and melted butter in a small bowl.
Line a muffin pan with 6 muffin cup liners. With a large spoon scoop the pumpkin batter into the muffin liners. They will be almost full and should evenly fill 6 cups, Top the middle of each muffin with a small spoonful of the pepita streusel.
Bake for 25 minutes. Remove from oven and allow to sit for 5 minutes before removing from the muffin pan. Let cool a few more minutes before enjoying. Muffins will stay fresh in a sealed container for up to 3 days.