Set aside all the other ingredients in individual bowls before starting.
In a large mixing bowl, add the yeast, sugar, flours, eggs, salt and warm milk and start kneading ( alternatively one can add all the ingredients to a stand mixer, attach the dough hook and start kneading)
Knead the dough just till all the ingredients come together (Over kneading increases the gluten in the dough and the buns become dense after baking)
Grease another large mixing bowl with little oil and lay the dough into that.
Cover the dough with cling film or a plate and let it rest for 45 minutes to 1 hour ( or till the dough doubles in size).
Remove the plate / cling film, punch down the dough and knead a little a bit.
Portion out the dough into small balls and set aside ( i weighed each ball to approximately 70 – 75 gms)
Grease a baking tray and set aside.
Tighten by rolling each ball between your palms and tucking the skin / edges to get a smooth skin on top.
Roll all the dough balls and place them slowly on the baking tray ( leave at least 1 inch space between each ball).
Cover with a wet towel or cling film and let it rise for another 30 minutes ( till the dough balls double in size).
While the dough balls are resting pre-heat the oven to 200 degree C.
Once the dough balls rise, remove the cling film, apply egg wash using a brush and sprinkle sesame seeds on them.
Bake the buns in the oven for 15-20 minutes or till it turns golden brown in colour.
Once baked remove the buns and set aside for 5 minutes ( always wear mittens while removing anything hot from the oven). Apply butter on top of the buns while they are hot.
Remove the buns from the tray and set aside on a wire mesh to cool.( cover them with a dry towel so that the top does not dry out)