In a medium bowl, whisk together sugar, salt, and egg yolks until smooth. Set aside.
In a medium saucepan, heat milk and heavy cream until it just starts to bubble around the edges.
Whisk hot milk mixture into egg mixture in small amounts to avoid cooking the eggs.
Return mixture to saucepan.
Cook and stir over medium low heat until it coats the spoon, about 8-10 minutes.
Remove from heat.
Strain through a fine mesh sieve into a clean bowl.
Stir in molasses and spice.
Place in a water bath to chill, or cover and refrigerate.
When cold, pour into ice cream machine.
Follow manufacturer's directions for freezing.