Healthy carrot cake with lemon cheese frosting - by Felicia Tan

Healthy carrot cake with lemon cheese frosting, using grape seed oil. Very moist Can anyone tell me why there are so many bubbles on the surface of the cake?

Carrot Cake Recipe
Ingredients
Original recipe makes 1 - 9x13 inch pan
2 cups all-purpose flour
2 teaspoons baking powder
2 teaspoons baking soda
1/2 teaspoon salt
2 teaspoons ground cinnamon (I use only ¼ tsp so that the smell is not that strong)
2 cups white sugar (I use only ¾ cup raw sugar)
4 eggs (I use AA size)
1 1/3 cups vegetable oil (I use grapeseed oil)
4 cups grated carrots
3/4 cup chopped walnuts

Directions
1. Preheat oven to 350 degrees F (175 degrees C). (My oven is hotter so I set my oven as 160C for 42 mins) Grease and flour a 9x13 inch pan. Sift together the flour, baking powder, baking soda, salt and cinnamon. Set aside.
2. In a large bowl, mix together the sugar and eggs until thick and pale. Stir in the oil, then gradually mix in the sifted dry ingredients. Fold in the carrots and nuts. Spread evenly into the prepared pan.
3. Bake for 40 to 45 minutes in the preheated oven, or until a toothpick inserted into the cake comes out clean. When cool, frost with your favorite Cream Cheese Frosting.

Lemon Cream Chesse Frosting
Ingredients
4 ounces cream cheese
1/4 cup butter, softened
1 cup icing sugar (I use ½ cup)
2 tablespoons lemon juice (I use one whole lemon juice)
(I also add one whole lemon zest)

Diirections
1. Beat cream cheese and butter in a bowl until combined. Beat in icing sugar and lemon juice.