How To Make Chocolate Swirl Cake | Castella Sponge Cake

Turn a wonderfully rich butter cake into a treat worthy of a celebration with some lovely effect and a few creative details and that are perfect for adding to your Christmas table or to give it as a delicious gifts to your loved ones.

Ingredients

(A)
• 35g, 3 tbsp butter
• a pinch of salt
• 33g, 3 tbsp milk
• 20g, 2 tbsp sugar
• 55g, 61/2 tbsp cake flour
• 3 large egg yolks, cold

(B)
• 3 large egg whites, cold
• 1/2 tsp lime / lemon juice or 1/4 tsp cream of tartar
• 50g, 5 tbsp sugar

(C)
• 1 tsp cocoa powder, sieved

(D)
• softened butter - for greasing the cake pan
Prepare muffin tin with 9 holes,  6-inch cake pan / 23cm square, round baking pan or loaf tin and using paper rub a little butter and cut a round piece and corner of parchment paper that fit to your pan, 

Method:
Pre-heat oven, always bake with both top and bottom heat with fan assisted. To make sure your cake to succeed even better. It is best to use an oven thermometer and you'll always have the exact temperature of your oven in mind. 

1) Heat the butter in a saucepan, over low heat, Add a pinch of sea salt, milk and sugar until it dissolves. Turn off the heat, sift the cake flour, add the egg yolks and mix by hand until just combined. do not over mix!

2) In a separate bowl, Whisk (B) egg whites until foamy then squeezing a little lime or lemon juice and add sugar a little bit at a time, beating until to a thick and stiff peak stage, about 3-5 minutes.

3) Using a whisker, and turn the small amount of egg whites into the batter, mix well and then turn back the batter into the whites, the most important part here is not to stirring and carefully folding is gentle mixing technique until just incorporated.and use a spatula and smooth the surface. Bang the cake pan a few times and get the air bubbles out of your cake batter.  

4) Use 1 tbsp cocoa powder, mix with the remaining batter. To fill the piping bag neatly, stand it in a glass, spoon your chocolate batter in and secure the bag closed and snip off the corner. Gently squeeze and use a chop stick or whatever tools can create any pattern you wanted on the top of cakes before you bake it to get a lovely effect.

5) To prepare a water bath. Pour enough cold water in a larger pan. Bake in preheated oven 150°c for 18 minutes - cupcakes. 45 minutes - 9 inch cake pan or until the cake is set in the centre. Baking time it will depend on the size of your cake pan. Rest in the oven at least 10 minutes.

6) Once the cake is cool, remove the lining. Transfer the cake to a plate for serving. Cut to any shape of your desired. Any leftover cake can be covered and kept in the fridge for 2 days.

Helpful Tips:
1) Be careful not to get the saucepan hot because the oil will burn. 
2) For guaranteed results it's important to follow exactly this recipe and baking at the right temperature is important. It's recommended to use an oven thermometer.
3) Do not bake the cake quickly at a high temperature and don't remove hot cake out of a baking pan. otherwise the cake could fall apart and crack on top. Baking cake at a lower temperature will help the cake rise much higher and bake more evenly.
4) Please understand that everyone's oven work differently. You should also check the temperature of your oven. if not, your cake won't rise well. 
5) You can test the cake by poking it with a skewer, if it's cooked the skewer will come out clean. if not pop it back in the oven and bake until it's ready. 
6) Folding egg whites into a cake batter. Do not stir and never use an electric mixer. 
7) Use a clean, dry bowl, free of yolk and any other oil or grease while beating egg whites. Do not over or under-beat the egg whites.
8) If it's cooked the skewer will come out clean. if not pop it back in the oven and bake until it's ready. 

Recipe Source: JosephineRecipes.Co.Uk