Combine the pumpkin, sugar, egg and oil in a medium mixing bowl and mix until well combined.
In a medium bowl combine flour, cinnamon, nutmeg allspice, baking powder, baking soda, and salt. Mix to combine. Add to pumpkin mixture. Mix until fully combined.
Pour batter into prepared baking dish, and spread to cover the bottom of the pan.
Bake for 20-25 minutes or until a toothpick inserted in the center comes out clean.
Cool on a wire rack.