Preheat oven to 400˚F. Line 12 standard-size muffin cups with paper liners or coat with cooking spray. 

In a large mixing bowl, combine the flour, baking powder, salt, pumpkin pie spice, and walnuts. 

In a medium mixing bowl, beat the eggs and brown sugar until well combined. Add the eggnog, butter, and extracts, and blend well on low speed. 

Add the egg mixture to the flour mixture. Mix the wet and dry ingredients with a spoon until just combined. Do not over mix. The batter will be slightly lumpy. 

Divide batter evenly among the muffin cups. Bake 12 to 14 minutes or until a toothpick inserted in the center of the muffin comes out clean. Remove muffins from pan and allow to cool.