Delicious and fun 'Coffee Breakfast Bun with Exploding Filling'

Prepare the ingredients.

Pour all ingredients except the butter into the food processor and blend into a dough.

Then add the butter and knead until a thin film forms.

Then place it in a container and let it ferment until it doubles in size.

Beat the egg yolks and granulated sugar together until slightly pale, then sift in the cornstarch and mix evenly, setting aside. Next, pour the coffee powder into the milk and stir to combine, heating over low heat until small bubbles appear.

Then, pour it into the egg yolks while stirring, and after mixing evenly, heat on low heat.

Keep stirring until thickened, then remove from heat and let cool for later use.

Take out the well-fermented dough to release the air, divide it evenly into portions, roll them into balls, and place them on a baking tray.

Place in the oven and set to 35 degrees for 40 minutes, ferment until it is 1.5 times larger. After fermentation, adjust the oven to 170 degrees and bake for 20 minutes, then cover the top with aluminum foil and bake for another 10 minutes.

Remove it and, after cooling, pour in the coffee custard sauce.