In a large bowl mix flour (90g), baking soda (1 tsp), salt (1/8tsp, but if you use salted butter, you can delete salt).
Cream 60g butter till creamy and smooth. Add 70g sugar, mix them till light and fluffy. Then add in 2 small eggs (one at a time) and 1/2 tsp vanilla.
Add flour mixture into butter mixture. First, 1/3 flour mixture, 15g milk. Then 1/3 flour mixture, another 15 g milk. And last add in all the rest flour mixture.
Beat till flour all mix in.
Preheat oven to 180 degree C and bake for 17-20 mins.