Boil/steam the potato till it's soft enough to be mashed and set it aside

In a mixing bowl, mix 200gr of bread flour, 2 tbs of extra bread flour, 3 tbs of wheat flour and instant yeast

In a jar, add sugar into the milk and then after the mashed potato is cool down, add the liquid into mashed potato and mix it evently

Pour the mixture into the dry ingredient and knead it softly till it combine. Let the dough rest for 15 minutes

After 15 minutes, put out the dough to the working surface, and butter, and knead for about 10 minutes till the dough is elastic enough just like a window pane stage

After it becomes elastic, put it back to the mixing bowl and grease it with a lil bit of oil and let it rest for 1 hour or untill it double it size

After 1 hour, flatten the dough, devide into equal pieces, make a round shape and leave for 15 minutes

After 15 minutes, flatten the dough, shape it into a roll it then put it into the loaf pan. Leave it rest for another 1 hour

Preheat the oven, bake your bread n 180C for 30 minutes