1. Put the butter and milk in a small pot and heat until melted and set aside.
2. Add a few drops of white vinegar to the egg whites, and then add fine sugar three times to beat until sharp corners.
3. Add the egg yolk and continue to beat with an electric whisk.
4. It is enough to beat until the dripping batter does not disappear.
5. Sift in low-gluten flour and use a spatula to cut and mix evenly (do not stir in a circular motion).
6. Take one third of the batter and mix it with the butter and milk liquid that has been melted in the first step.
7. Stir the mixed batter with the remaining two-thirds of the batter and mix well.
8. Pour the cake batter into the 11-inch deep baking pan (shaking the baking pan a few times), leave a little batter in the basin, add a little cocoa powder, stir evenly, and put it in the piping bag.
9. Squeeze the cocoa paste on top one by one, and then swipe up and down with a toothpick to make the pattern appear.
10. After preheating the oven at 180 degrees for 10 minutes, put it in the middle layer and bake for 30 minutes. After being released from the mold, it can be cut into pieces after a while.
Tips:1. If you don't like too sweet, the amount of sugar can be reduced, but not less than 60 grams.
2. The average size of eggs in the recipe is 60 grams.
3. Each oven has a different temper. The baking temperature and time are for reference only.
