Mix flour, sugar, salt & baking powder together(dry ingridients) then whisk egg yolk, milk & butter, whisk very well & add in the dry ingridients. Using mixer mix the egg white very well until it foams then add into the batter then mix well.

Then heat ur masa pan sprinkle some oil or butter then add in some of the batter & drop some jam inside then add in a lil batter to cover the jam then u flip when its done. this measurement is for 1 round if you want 2 rounds then u double the measurement.