Prep the pan: Heat the oven to 350°F (175°C). Line a mini muffin pan with paper liners or lightly grease with oil or baking spray.
Mix wet ingredients: In a large bowl, whisk pumpkin puree, brown sugar, granulated sugar, oil, eggs, and vanilla until smooth and glossy.
Combine dry ingredients: In a separate bowl, whisk all-purpose flour, whole wheat flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
Bring it together: Add the dry ingredients to the wet.
Stir gently with a spatula until just combined. A few small streaks of flour are okay.
Fold in add-ins: If using chocolate chips, nuts, or raisins, fold them in now. Do not overmix.
Fill the cups: Spoon batter into the mini muffin wells, filling each about 3/4 full.
This helps them dome nicely.
Bake: Bake for 11–14 minutes, until the tops spring back and a toothpick comes out with a few moist crumbs.
Cool: Let muffins rest in the pan for 5 minutes, then transfer to a rack to cool completely. Enjoy warm or at room temperature.