01 -
Preheat the oven to 425°F. Line a 12-cup muffin tin with paper liners or grease thoroughly with butter to prevent sticking.
02 -
In a small bowl, combine melted butter, flour, granulated sugar, brown sugar, and cinnamon. Mix with a fork until the mixture forms coarse crumbs that hold together when squeezed but remain sandy.
03 -
In a large mixing bowl, whisk together all-purpose flour, pumpkin pie spice, cinnamon, baking powder, baking soda, and salt to ensure even distribution.
04 -
In a separate bowl, whisk the pumpkin purée until smooth. Add vegetable oil, sour cream, eggs, vanilla extract, brown sugar, and granulated sugar. Beat until fully combined with no visible streaks.
05 -
Pour the wet ingredients into the dry mixture. Gently fold with a spatula until just combined, stopping as soon as no dry flour remains to maintain tenderness.
06 -
Scoop batter evenly into muffin cups, filling each about two-thirds full. Generously sprinkle streusel topping over each muffin and lightly press to adhere.
07 -
Bake at 425°F for 5 minutes, then reduce oven temperature to 375°F without opening the door. Continue baking for 15 to 18 minutes or until a toothpick inserted in the center comes out with a few moist crumbs.
08 -
Allow muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely. Serve warm or store appropriately.