Step 1

Fill a medium saucepan with 1 inch of water and bring to a simmer over high heat. Reduce to low. Meanwhile, in a large bowl, whisk the egg yolks with the salt, sugar, and cinnamon until sugar is dissolved and mixture falls from whisk in creamy pale yellow ribbons, about 4 minutes. Whisking continuously, pour in liquor.

Step 2

Place bowl over simmering water and cook, whisking continuously, until mixture is thick enough to form a coat on the back of a spoon, about 8 minutes total. (If using thermometer, mixture should reach at least 130°F).

Step 3

Remove from heat and whisk in vanilla. Pour into a sealable glass container and refrigerate for a minimum of 6 hours before serving. Store in the refrigerator for up to 1 month.