Purple Sweet Potato Butter Cake 紫薯牛油蛋糕

I baked this purple sweet potato butter cake as I have some steamed purple sweet potato leftover after baking my Purple sweet potato bread. The purple sweet potato, which only present in small quantity in this cake recipe, was not strong enough to affect the aroma of the butter cake. It just helped to make some nice contours in the moist and velvety cake :)

Pan size: One 26Lx10Wx7H cm loaf pan

Ingredients

Ingredients in room temperature

110g unsalted butter, softened 无盐牛油，软化
105g fine sugar 细糖

3 eggs 鸡蛋

110g top/cake flour 低筋面粉
15g milk powder 牛奶粉
1/2 tsp baking powder 泡打粉

20ml lemon juice 柠檬汁

15g honey 蜂蜜

1/2 tsp lemon zest 柠檬皮削

1/2 tsp vanilla essence 香草精

40~50g steamed purple sweet potato paste 

Directions

1. Coat the loaf pan with butter, followed by dusting some top flour over it. Set aside.

2. Mash the steamed sweet potato into paste. Cover and set aside.

3. Collect 20ml of lemon juice, and 1/2 tsp of lemon zest from a lemon. 

Pour lemon juice, honey, lemon zest, and vanilla essence, in a small bowl.  Set aside.

4. Cream softened butter and fine sugar, till pale and fluffy using a hand whisk. Set aside.

5. Beat eggs till frothy.

Add beaten egg into the butter cream from (4) gradually.  Start adding the next batch of beaten egg after the previous batch has been well incorporated with the butter cream.

6. Mix top/cake flour, milk powder and baking powder in a separate mixing bowl before sifting into the butter cream mixture.

7. Blend in the lemon-honey mixture from (3).

Give the batter a more thorough mix using a spatula.

8. Take about 1/4 of the batter and mix with the purple sweet potato paste from (2).

9. Pour the two batters into the prepared loaf pan in alternating sequence - adding new scoop of batter on top of the previous one to create the line pattern​.

10. Bake at middle rack of a preheated oven set at 150° Celsius for 40 minutes. Increase the oven temperature to 170° Celsius for additional 5 minutes to give a nicer brown top.

 End of baking

Let the cake cool down in the loaf pan for about 10 to 15 minutes over a wire rack before inverting it out to cool further.

11. Cut the cake after it has cooled down. Enjoy 😋🍰