Preheat the oven to 350 °F and line a 9x9 inch square (or round) baking pan with parchment or a silicone line.
In a large bowl, whisk together the brown sugar, oil, eggs, pumpkin and vanilla until combined.
Whisk in the baking powder, soda, salt and spices until mixed.
Mix in the flour until just incorporated. Fold in the carrots. Pour batter into prepared pan.
Bake for 25-30 minutes until the centre lightly bounces back to the touch and a toothpick inserted into the centre contains just a few crumbs.
Remove from the oven and set on a wire rack to cool for at least two hours.
Frost with cream cheese icing if desired and serve.
Notes
LeftoversStore leftover unfrosted cake at room temperature for up to 4 days or freeze for up to 3 months. Frosted cake should be kept in the refrigerator for up to 4 days or frozen for up to 3 months.