Vanilla pudding

Whisk sugar, cornstarch, and salt in a saucepan.

Whisk in milk until smooth.

Cook over medium heat while stirring constantly.

In a bowl, whisk egg yolk.

Slowly add some hot mixture to the egg yolk while whisking.

Return mixture to saucepan and continue cooking.

Cook until thick and bubbling.

Remove from heat and stir in butter and vanilla.

Pour into serving dishes and cool or chill.