Preheat oven to 350 degrees F (175 degrees C). Grease or line 3 muffin pans. Mix pumpkin, sugar, applesauce, oil, and eggs together in a bowl until well blended; fold in pumpkin seeds. Mix flour, baking soda, cinnamon, nutmeg, pumpkin pie spice, salt, and baking powder together in a separate bowl. Stir flour mixture into pumpkin mixture until just combined; pour batter among prepared muffin cups. Bake in the preheated oven until a toothpick inserted in the center of a muffin comes out clean, 20 to 25 minutes.