Preheat the oven to 350°F.
In a large bowl, whisk together the almond flour, coconut flour, ½ cup of sweetener, baking powder, pumpkin pie spice and salt.
In a separate bowl, combine the eggs, pumpkin puree, almond milk, melted butter and vanilla.
Add the wet ingredients to the dry ingredients and stir just until combined.
If using walnuts, gently fold them into the batter.
Line 18 muffin cups with paper liners and divide the batter evenly among them, filling each about three-quarters full.
In a small bowl, combine the remaining 1 tablespoon of sweetener with the cinnamon. Sprinkle the cinnamon mixture evenly over the tops of the muffins.
Bake the muffins for 25 to 30 minutes or until a toothpick inserted in the center of a muffin comes out clean.
Cool the muffins in the pan for five minutes, then transfer them to a wire rack to cool completely.
