1. Mix sugar A, corn starch and egg yolk together and stir.

2. It is very important to stir until it is slightly white to prevent caking at the back.

3. Mix and heat milk and sugar B, boil (bubble), slowly pour into the egg yolk paste, and stir while pouring.

4. Then, while stirring, the material in step 3 is tempered and heated, gradually changing from liquid to paste.

In the process of heating, before the paste is formed, it should be stirred quickly to prevent the bottom from pasting and sticking.

5. Add butter, the temperature of the paste will melt the butter, and keep stirring until there are no particles.

6. Let it cool for a while, put it all into fresh-keeping bags, dilute and flatten it, and put it in the refrigerator for refrigeration. The purpose of this is, first, to cool quickly, second, not to produce condensed water, and third, not to produce crust.

7. The finished cheese sauce is very mellow, and many products can be used as fillings.