In a large mixing bowl, combine all-purpose flour, instant yeast, baking powder, sugar, and salt.

Gradually pour in full-fat milk while mixing until a dough begins to form.

Knead the dough for about 5 minutes until smooth and elastic.

Let it rest covered for 10 minutes, then knead again for another minute.

Place the dough in a greased bowl and cover it with a damp cloth, letting it rise in a warm place until doubled in size, approximately 1 hour.

Punch the dough down to release air and divide into 12 equal pieces.

Shape each piece into a ball and roll into an oval about ¼ inch thick.

Brush a small amount of vegetable oil on each oval and fold it over to create the bao shape.

Place the shaped buns on squares of parchment paper.

Arrange the bao buns in a steamer basket lined with parchment paper, ensuring they are not overcrowded.

Cover with a kitchen towel and let them rise for 15 to 30 minutes.

Bring water to a gentle boil over medium heat and place the steamer basket over the pot.

Steam the buns for about 10 minutes, then let them rest covered for an additional 5 minutes.