Preheat oven to 350 degrees. Line a muffin pan or spray well.
In a medium bowl, make the flax egg by combining the ground flaxseed and water. Stir and set aside for 5 minutes to thicken.
In a large bowl, add the flour, cinnamon, pumpkin spice, baking powder, baking soda, and salt. Whisk until well combined.
In the bowl with the flax egg, add the mashed sweet potato, avocado oil, almond milk, coconut sugar, and vanilla. Whisk until well combined and smooth.
Add the wet to the dry. Stir with a spatula until combined. Careful not to over mix! Divide the batter into the muffin tins. Make the streusel by combining the oil, coconut sugar, flour, cinnamon, and chopped pecans in a small bowl. Stir until combined. Sprinkle streusel evenly on the tops of the muffin batter.
Bake for 20 minutes, or until a toothpick comes out clean. Let it cool in the pan for 10 minutes. Carefully remove muffins from the pan and place on a wire rack to cool completely. Enjoy! Store in an airtight container on the counter for 3 days.