Preheat the oven to 375F and line 12 muffin tins.
To a large bowl, whisk together the pumpkin puree, egg, vanilla, oil, maple syrup and milk.
Add the spices, baking soda, salt, whole wheat flour and oats and mix until just combined. Gently fold in the chopped walnuts and chocolate chips.
Scoop the batter into the 12 lined muffin tins, diving the batter equally.
Place in the oven and bake for 18-20 minutes or until the tops are slightly golden brown and the middle is set. Allow to cool in their tins for about 5 minutes then transfer to a cooling rack.
Once completely cooled, store in an airtight container in the refrigerator for up to 5 days. Serve heated up with nut butter or yogurt as a quick breakfast or for a snack. Enjoy!