MRS NgSK's BUTTER CAKE

MRS NgSK's BUTTER CAKE

(I adapted this recipe from here.  I made the changes in blue)

Ingredients 
230gm butter (salted), softened (cool at 18-20C, not glossy)
200gm eggs, no shell (4 grade B eggs)
50gm + 150gm sugar ( reduced the 150g sugar to 100g)
200gm self raising flour, sifted.
60ml milk
1 vanilla bean, seeds scraped (or 1 tsp vanilla extract)

Method
1. Preheat oven at 180C (conventional). (I only use 170C). (I baked at 180C) Prepare a 8 inch square pan. Line the base and grease the sides (greasing helps the cake’s sides to rise well)
2. Separate the eggs, and place the whites into a medium sized bowl (6 cup capacity)Beat egg whites until soft peaks, gradually add 50gm sugar and beat until stiff. Set aside.
3. Cream butter and 150gm sugar (I used 100g) until pale and fluffy (KA speed 2-4 ). Put in vanilla seeds and and beat for a while. Put in egg yolks one by one and beat well after each addition.
4. Put in half the flour and mix on low speed until incorporated. Put in milk in 2 additions and mix until well incorporated. Mix in balance of flour.
5. Put half the egg whites in and mix on low speed. Pour the balance of egg whites in and FOLD.
6. Pour batter into pan and level.
7. Bake for 45 minutes or until skewer comes out clean. (I reduced to 150C for the last 15 minutes because the top seems to be getting dark)

*Note: I did step 2 and 3 simultaneously. Butter in the stand mixer and egg whites with the hand mixer.