Mexican Coffee buns

For Buns:
-Bread flour 300g
-Salted Butter 30g
-White sugar 50g
-Dry Yeast 11g
-1 egg
-Water 140ml

For Topping:
-2 eggs
-Cake flour 100g
-Salted Butter 100g
-Coffee Emulco 1  1/2tsp
-Caster sugar 50g