1. In a medium saucepan, heat milk, ginger, and spices. Bring to a gentle boil, cover, and remove from heat. Steep for 30 minutes. Strain mixture, and reserve milk; discard solids. Stir in molasses until well mixed.

2. Combine egg yolks and sugar in the bowl of an electric mixer. Beat at medium-high speed until very thick and pale yellow, 3 to 5 minutes. Meanwhile, return milk to a simmer.

3. Add half the milk to egg-yolk mixture, and whisk until blended. Stir into remaining milk, and cook over low heat, stirring constantly, until mixture is thick enough to coat a spoon.

4. Remove from heat, and immediately stir in cream. Pass mixture through a strainer into a medium bowl set over an ice bath to chill. Freeze in an ice-cream maker according to manufacturer's instructions. Store in a plastic container.