Pumpkin Chocolate Chip-Walnut Muffins

Oh, what a delight these muffins are!  The flavors are absolutely perfect together!  I can eat this all day! Enjoy!
Ingredients (this recipe makes about 18 regular muffins):
-6 Tbs salted butter, melted
-1 cup packed pumpkin
-1 cup packed brown sugar
-3/4 cup milk
-2 large eggs
-1 Tbs baking powder
-1 1/2 tsp pumpkin pie spice
-2 1/2 cups flour
-1 cup semisweet chocolate chips
-1/2 cup chopped walnuts
Preheat oven to 400 F.  Line 18 muffin cups and set aside.
In your mixer's bowl, beat the melted and slightly cooled butter with the pumpkin, sugar, milk and eggs.  Mix until well blended.
Add the baking powder, spice and flour, half a cup at a time.  Stir in the chocolate chips and walnuts.
Spoon evenly into prepared muffin pans.
Bake in preheated oven for 15-17 minutes or until toothpick comes out clean.
Cool in the pan for 10 minutes, then on wire rack until complete.  Enjoy!