Preheat the oven to 375 degrees and grease a muffin tray.
In a medium-sized mixing bowl, add the pumpkin puree, brown sugar, almond milk and vegetable oil. Whisk to combine.
Sift the all-purpose flour, pumpkin pie spice, baking powder and salt into the puree mixture.
Stir the ingredients together being careful not to over-mix. Fold in the chopped walnuts.
Fill the muffin cups to (almost) the top of the brim. Bake for 24-26 minutes or until a toothpick inserted into the center comes out clean. Let cool and remove the the tray.