Marble Butter Sponge Cake
60g unsalted butter
85g self raising flour
4 egg yolks (from 65g eggs)
1 tsp vanilla extract
1/4 tsp salt
1 tablespoon cocoa powder (sifted)
4 egg whites
75g caster sugar
1/4 tsp cream of tartar
Utensil: 7″ round, grease sides and line bottom.
Oven preheated to 160C, water bath method, lowest level.
1. In a pot, heat butter until just bubbly, switch off fire, then add 2/3 of the flour, stirring until smooth.
2. Add milk, salt and vanilla extract and stir to combine. Nexby egg yolks. Lastly, add the last portion of flour and mix until smooth. Set aside while you prepare the meringue.
3. Place eggwhites into a stand mixer bowl and beat until frothy before adding the cream of tartar and continue to beat until foamy. Gradually add sugar until firm peaks.
4. Add 1/3 of the meringue into the yolk batter and mix with hand whisk until lightened. Then add another portion and keep mixing until incorporated. Use a spatula to scoop from bottom of pan and fold up to ensure batter are properly mixed. Divide batter into 2 equal portions and add cocoa powder into one. Mix gently until incorporated.
5. Pour both batters together, side by side, into prepared pan and baked in water bath at 160C for 70-80 minutes. Insert a piece of foil on the highest level for the first 40 minutes of baking. Remove it after 40 minutes and continue baking for 30 minutes then test by pressing lightly on the surface. If still squishing, bake longer.
6. Remove and unmould immediately to cool on wire rack.