Prepare the Oven. Preheat your oven to 350°F and line a muffin tin with paper liners or lightly grease with oil spray.
Mix Wet Ingredients. In a large bowl, whisk together the pumpkin puree, eggs, maple syrup (or honey), oil, and vanilla extract until smooth.
Add Dry Ingredients. Stir in the whole wheat flour, baking powder, baking soda, pumpkin pie spice, cinnamon, and salt until just combined. Do not overmix to keep muffins tender.
Add Optional Mix-ins. Fold in nuts or chocolate chips if desired.
Divide Batter. Scoop the batter evenly into the prepared muffin tin, filling each cup about 3/4 full.
Bake. Bake for 20-22 minutes, or until a toothpick inserted in the center comes out clean.
Cool & Serve. Let muffins cool in the pan for 5 minutes before transferring to a cooling rack. Serve warm or at room temperature.