To start, preheat the oven to 200°C (approximately 400°F).
In a spacious mixing bowl, prepare the batter by combining sugar, butter, baking powder, kosher salt, vanilla extract, all-purpose flour, milk, and one egg. Whisk the mixture until it achieves a smooth consistency.
Take the mini loaf pans and generously grease the bottoms and sides with cooking oil. Fill each pan to about half capacity with the batter, making sure to evenly divide it into three equal portions.
Take two pieces of mozzarella cheese and position them along the edges of each batter, leaving an open space in the center for placing the egg.
The next step is to crack one egg on top of the batter in each pan. Then, place the pans in the oven and allow them to bake for approximately 13 minutes.
Bring out the just-baked Korean egg bread and indulge in it with your loved ones!