1. Grease and flour a 9" square pan.
2. Combine dry ingredients in a mixing bowl. I sift the baking powder through a wire mesh strainer to break down clumps.
3. Add the shredded carrots and mix well into the batter. Use a fork to blend the eggs, vanilla, and Mayonnaise with the batter.
4. Spread batter evenly in pan and bake at 325 F degrees (or 200 C). The original recipe requires a 50-minute baking time. However, my toaster oven can cook this cake in 15 minutes with top and bottom heaters on.
5. Cool cake about 30 minutes. Frost with Cream Cheese Frosting.
Frosting: Place butter and cream cheese in a small bowl and heat small bowl in boiling water. Could use a small saucepan and warm under very low heat. After butter has melted, sprinkle powered sugar and blend ingredients together.
Tips: This cake tastes much better by reducing the sugar. I reduced the sugar in the batter by 1/4 cup. Similarly, I sprinkle enough powered sugar to give the frosting a little sweetness.