Preheat the oven: Preheat your oven to 350°F (175°C). Grease a 24-cavity mini muffin pan or line it with mini muffin liners.
Mix the dry ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, pumpkin pie spice, and salt.
Mix the wet ingredients: In a separate large bowl, whisk together the pumpkin puree, granulated sugar, brown sugar, egg, vegetable oil, and vanilla extract until smooth.
Combine: Gradually add the dry ingredients to the pumpkin mixture. Stir gently until just combined. Avoid overmixing.
Fill the pan: Spoon the batter into the mini muffin cavities, filling each about two-thirds full.
Bake: Bake for approximately 10–14 minutes, or until the muffins are puffed and a toothpick inserted into the center comes out clean or with a few moist crumbs.
Cool: Let the muffins cool in the pan for about 5 minutes, then transfer them to a wire rack to cool completely.