(a). 173g butter, 292g powdered sugar, 5g salt, 10g SP (cake emulsifier)
(b). 52g whey protein powder, 187g water, thoroughly mix and set aside
(c). 265g cake flour, 4g baking powder, thoroughly mix and set aside
(d). 80g evaporated milk
(e). 17g cocoa powder, 1g baking soda, 21g hot water
(f). One loaf pan with size 20×10.5×10.5cm
(1) Preheat oven to 355ºF (180ºC). Mix ingredients (a) in a mixing bowl and beat with electric mixer at low speed until completely blended then change to high speed to beat for about ten minutes until fluffy. Add mixture (b) 1/3 at a time and blend well with electric mixer after each addition. Add mixture (c) 1/3 at a time also and mix with rubber spatula after each addition. Finally add evaporated milk and blend well.
(2) Mix ingredients (e) thoroughly and combine with 280g batter from (1) to make chocolate batter.
(3) Grease and flour the loaf pan. Pour 1/2 batter then all the chocolate batter and finally, the rest of batter on top. With a bamboo stick, gently draw swirls through the batter to marbleize it.
(4) Bake in preheated oven for about 50-60 minutes.