Preheat your oven to 425°F and line a 12-cup muffin tray with liners or use baking spray.
In a medium bowl, combine the flour, pumpkin spice, cinnamon, baking soda, baking powder, and salt. Whisk until combined.
In a large bowl, blend the pumpkin puree with the sugar and brown sugar until smooth. Stir in the eggs, oil, milk, and vanilla extract until fully incorporated.
Slowly add the dry ingredients to the wet mixture, gently whisking until the batter is smooth and no streaks of dry flour remain.
Spoon the batter into liners, filling each one to the top.
Bake at 425°F for 5 minutes, then lower the oven temperature to 350°F and continue baking for another 16–17 minutes, or until a toothpick inserted in the center comes out clean.
Let the muffins cool in the pan for 5 minutes before serving. Store any leftovers in an airtight container at room temperature for up to one week.