Whisk together the heavy cream, whole milk, sugar and molasses in a saucepan. Add the ginger. Bring to a simmer over medium heat. Turn off heat.
Whisk together the egg yolks, vanilla, cinnamon, allspice, cloves and salt constantly for about three minutes. Reserve the egg whites for another use — we only want the yolks.
Add about ¼ to ½ cup of the warm cream mixture into the egg mixture, whisking constantly. This tempers the eggs to gently cook. Repeat this a few times.
Add egg-cream mixture back to the saucepan with the rest of the cream. Whisk constantly and bring back to a simmer. Cook until mixture thickens and covers the back of a wooden spoon.
Pour the mixture over a fine-mesh sieve into a large mixing bowl and place plastic wrap directly on top of the custard's surface. Refrigerate until cold.
Pour into an ice cream maker and churn. In the last couple minutes of churning, add the crushed ginger snaps. Pour into an airtight container and freeze for a few hours. Enjoy!