Coconut, Lemon Curd, and Mango Cake

I admittedly made this bake a few weeks ago, when I had some leftover coconut milk from a savory recipe and a lot of leftover mango. I was really determined to find a Bake Off challenge with which I could use up my leftovers before they went bad. I found that Series 8, Episode 1's signature challenge was to make a fruity cake! Coconut, mango, and lemon are all fruits, so this cake idea quickly formed.

I had a few issues with the construction of the cake (due to my own impatience), so it ended up only being two layers instead of the three I had planned. The recipe is for a three-layered cake, so keep in mind that the final result will be a little taller than seen in these pictures.

I had some homemade lemon curd in my refrigerator, but store-bought will do just as well. Likewise, store-bought mango jam will work just as well as my homemade jam.

The cake went over a storm at Vincent's office. One of Vincent's coworkers specifically loves lemon curd, so she really appreciated what I made here. Plus, everyone thought it looked quite nice.

One of the tricks to a light, airy cake is to use buttermilk as one of the liquids/fats. Due to the fact that I wanted to accomplish the coconut flavor by using coconut milk instead of buttermilk, I had to figure out another way to get a nice airy rise. The trick is to add a little bit of vinegar, which reacts with the baking soda. The reaction happens very quickly; it is important to mix the dry ingredients and the wet ingredients separately, and to be ready to put the cakes in the oven quickly after mixing together the wet and dry combinations.

Another contributing factor to the light, airy cake texture is the sifting of the flour. Clumps of flour are broken up through sifting, and the flour is encouraged to occupy more space, and therefore be less dense. This translates even after the flour is then mixed with other ingredients.

The mango jam is fairly easy to make- I have made it as more of a set jelly for the opera cake. Mango, sugar, and a tiny bit of water must be simmered over low heat for about 20 minutes. Some agar agar powder should be added in (just as a binder, since mango does not naturally have lots of pectin) shortly before the mixture is taken off of the heat and blended.

Lemon curd must also be made on the stove-top. It is actually quite easy to cook. Egg yolks, lemon juice, lemon zest, butter, and sugar are cooked together until thickened. The mixture can then be canned (or otherwise stored) and cooled.

The finishing touches for the cake are the coconut buttercream and some desiccated coconut for garnish. The coconut buttercream is pretty much like any other buttercream, except using coconut milk and coconut extract. The butter makes this frosting a little bit yellowish. This could be mitigated by making the frosting with vegetable shortening instead of butter (which would also make the frosting dairy-free). For some of the decoration, I set aside about 1/8 of the buttercream and colored it yellow and orange. Visually, the colorful decoration made the cake not look boring, and the chosen colors gave a hint at which flavors were contained within.

Next, I will be making a cinnamon cardamom chocolate orange babka from Series 7, Episode 3. But in between, I will update you with some Pi Day party coverage!

Instructions

Ingredients

For the cake:

1 C coconut oil, virgin

1 3/4 C granulated sugar

3 eggs, large, room temperature

3 C all purpose flour, sifted

zest of 1 lemon

2 tsp vanilla extract

2 tsp lemon extract

1 tsp coconut extract

1/2 tsp salt

1 tsp baking soda

1 tbsp baking powder

1 tsp cream of tartar

1 tbsp white vinegar

1 C coconut milk

For the mango jam:

6 oz fresh mango, cubed

6 oz granulated sugar

1 tbsp water

1/2 tsp agar agar powder

For the lemon curd:

4 lemons, juiced and zested

1 C granulated sugar

5 egg yolks

1/2 C (1 stick) butter, cubed

For the coconut buttercream:

1 1/2 C (3 sticks) butter, softened

5 C confectioner's sugar

1 tsp coconut extract

4-6 tbsp coconut milk

food coloring (optional)

Instructions:

1. Preheat oven to 350°F (180°C). Grease and line three 9" round cake pans.
2. For the cake, mix coconut oil, granulated sugar, eggs, lemon zest, vanilla extract, lemon extract, coconut extract, vinegar, and coconut milk in one bowl. In a separate bowl, toss together the sifted flour, salt, baking soda, baking powder, and cream of tartar. Mix the wet and dry mixtures together until fully incorporated. Quickly divide into the three cake tins and put them in the oven. Bake 30-40 minutes, or until springy and the toothpick comes out clean. Let cakes cool entirely before assembly.
3. To make the mango jam, place mango, sugar, and water in a saucepan. Bring to a simmer over low-medium heat. Let simmer 20 minutes. Add agar agar powder and let simmer 3 more minutes. Pour the mixture into a food processor or blender, and blend until slightly chunky.
4. To make the lemon curd, mix together the egg yolks and sugar together in a saucepan until light and airy. Add the juice and zest of the lemons, and then bring over low heat. Stir constantly until the mixture thickens. Add the butter, and fully incorporate. Bring off of the heat, pour curd into storage containers, and allow to cool in the refrigerator.
5. To make the coconut buttercream, cream the butter using an electric mixer or mixing stand. Slowly add in the confectioner's sugar. Then add in the coconut extract and the coconut milk. Start with 3 tbsp of coconut milk, and slowly add more until the buttercream becomes smooth and homogeneous, but still thick. Set aside 1/8 of the mixture for colored decoration if desired.
6. To assemble the cake, place one layer of the cake on a serving or decorating tray. Use a piping bag with a wide round nozzle to pipe a ring of buttercream around the edge of the top of the cake. Place the cake in the freezer 15 minutes, or until the buttercream is rather stiff. Add a layer of mango jam (about half the height of the buttercream ring) on top of the cake inside the buttercream ring. Let set in the freezer 15 minutes, or until stiff. Add a layer of the lemon curd and let set in the freezer 15 minutes, or until stiff.
7. Add the second cake on top. Repeat remaining stages of step 6. Add the third layer of the cake. Use the bulk of the remaining buttercream to frost the sides and top of the cake.
8. To decorate, color (if desired) the remaining buttercream, and pipe on top of the cake. Garnish with desiccated coconut. Refrigerate until serving.