• I use this mini loaf pan. It has 8 wells and each measuring 3.28 x 2.5 inches (8.3 cm x 6.35 cm), about 1 cup capacity in each well.

Prepare the sponge batter the day before:

• Empty 300 grams of sourdough discard into a mixing bowl or a container. Add milk and mix with a whisk or a spatula until combined.
  
• Add all-purpose flour and stir again to combine.
  
• Cover the bowl or container with plastic wrap or a lid. Place at a warm place, about 80-82 F (27-28 C) for 2-3 hours. The batter will rise some and you will see some air bubbles
  
• Rest the batter in the fridge for at least 8 hours or up to 24 hours

When ready to bake:

• Preheat the oven to 430 F (220 C) for conventional oven, 400 F (200 C) for convection oven
• Grease the baking pan with some oil. Make sure you grease them well so it's easier to release later
• Whisk 2 eggs, melted butter, salt, and sugar until the mixture emulsified
  
• Pour this over the chilled batter and use a spatula to gently fold the mixture to combine while rotating the mixing bowl as you are folding the mixture
  
• 
• This is how it should look like. All ingredients are well-combined
  
• Scoop the batter into the pan, filling about 1/2 full.
  
• Gently crack a cold egg on top of each batter.
  
• Cover the egg with some shredded cheese (to prevent the eggs from drying out during baking). You can also add a bit of diced ham, and bacon bits if you choose to do so
  

Bake:

• Place the pan on the middle rack and bake for 15-18 minutes. If you want the yolks to be still a bit custardy, bake for about 15 minutes. If you want them fully-cooked, bake for 18 minutes. The time is just for your reference. You need to adjust the timing based on your oven and the size of the mold you use.

Cooling:

• Remove from the oven and let them cool down in pan for 5 minutes and then use an offset spatula and run through the side of the egg bread to help you release it from the pan
  

Serving:

• Gyeran ppang are best served while they are still warm