Preheat oven to 350°F (175°C). Line a 12-cup muffin tin with liners or grease it lightly.

In a large bowl, whisk together pumpkin purée, eggs, oil, brown sugar, and vanilla until smooth and creamy.

In a separate bowl, combine flour, protein powder, baking soda, pumpkin pie spice, and salt. Stir so dry ingredients are evenly mixed.

Pour the dry ingredients into the wet mixture. Stir gently just until combined — avoid overmixing to keep muffins tender.

Spoon the batter evenly into the muffin cups, filling about 3/4 full. If using, sprinkle a few pumpkin seeds on top of each for a crunchy finish.

Bake for 20–25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.

Let muffins cool in the pan for 5–10 minutes, then transfer to a wire rack to cool completely before storing or serving.