Butter the sides of a heavy 2-quart saucepan.
Combine sugar, eggnog, whipping cream, salt and corn syrup and cinnamon bakery emulsion in pan. Stir over medium heat until sugar dissolves, and temperature reaches 236 degrees (soft ball stage*, if you don’t have a candy thermometer). The time for this will vary with stove temperatures, but expect to spend at least 20 minutes, up to 45.
Immediately remove from heat. Add butter, but do not stir.
Cool to lukewarm, 110 degrees.(This can take anywhere from 15-30 minutes. Don't rush it, but don't let it cool too long, either.)**
Add cranberries and stir vigorously until fudge stiffens and loses it gloss.
When it starts to stiffen, immediately push from pan into a buttered (or foil-lined and buttered, for easier removal) 8x8 pan.
Score while warm, cut when firm.