Cook the duck eggs. In a pot over medium heat, boil enough water to cover eggs. Gently place eggs in pot and simmer for 10 minutes. Peel and remove yolks. Cut salted egg yolks to fine pieces.
Make the filling. Mix the butter with icing sugar. Add in yolks and custard powder. Slowly stream in milk until mixed thoroughly. Refrigerate while you cut the croissants.
Slice the croissants in half. No need to cut through entirely.
Assemble salted egg yolk croissants. Preheat oven to 350F. Depending on the size of your croissant, spread 2 tbsp of filling in the center. Optional, place a dollop on top of the croissant. Bake for 2 minutes. Enjoy while it's warm!
Use fresh salted eggs for best-tasting results. Reserve the egg whites for a different dish. If they're not available, then the vacuumed sealed salted egg yolks will work as well.A kitchen scale will guarantee accurate results. I have included the measurements if you do not have one.It is best to use room temperature butter to ensure a smooth filling. Creaming the butter and sugar together initially will ensure a consistent filling without lumps.Use day old butter croissants. I buy my croissants from Costco instead of making them from scratch. This recipe is a quick and easy version and it's okay to cheat sometimes!Did you make this? Tag @cookwith.chopsticks and #cookwithchopsticks to share or leave a comment on the blog!