Preheat oven to 375 degrees. Spray regular or mini muffin tin with cooking spray or add liners.
In a large mixing bowl, add the coconut oil and brown sugar. Beat with a hand mixer until well combined. Add egg, pumpkin, and molasses, and beat until combined.
In a separate bowl, whisk together the flour, pumpkin pie spice, baking soda and salt. Gradually add the dry ingredients to the wet ingredients stirring to combine. Make sure you only mix until combined - over mixing causes and more gummy and dense muffin.
Spoon even amount of mixture into each mini muffin cup, filling about 3/4 full. Sprinkle with chopped walnuts or mini chocolate chips if you want. Bake 12-15 minutes for mini muffins, and 15-17 minutes for regular muffins, or until a toothpick inserted comes out clean. Remove from muffin tin and transfer to a cooling rack. Enjoy!