Preheat oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners.
In a medium bowl, whisk flour, pumpkin pie spice, baking soda, and salt.
In a large bowl, whisk pumpkin purée, granulated sugar, oil, eggs, and vanilla until smooth.
Add dry ingredients to wet and stir just until combined. Fill liners about ⅔ full.
Make streusel: mix both sugars, flour, and cinnamon; pour in melted butter and stir to coarse crumbs. Sprinkle evenly over batter.
Bake 20–25 minutes, until a toothpick in the center comes out clean or with a few moist crumbs.
Cool 5 minutes in the tin, then transfer muffins to a rack to cool completely.