Spray the loaf pan heavily with vegetable spray and sprinkle with the wheat bran, shaking the pan to coat on all sides--this will prevent sticking.
In a bowl whisk together the almond flour, sugar substitute, baking powder, pie spice, and salt. In another bowl, beat the eggs and then whisk in the pumpkin and vanilla. Combine the dry and wet ingredients and stir until combined. Pour the batter into the prepared pan and stir to combine.
Bake until golden brown and a toothpick comes out clean when stuck in the center, about 1 1/2 hours. Cool completely before removing from the pan. Slice into 12 portions.