The day before you make the ice cream freeze the ice cream insert for a full 24 hours.
Add the sweet potato puree to a large bowl along with the half-and-half, beer, light brown sugar, cinnamon, ground ginger, allspice, and salt. Whisk together until smooth. Cover with plastic wrap and chill the mixture thoroughly before churning.
Churn in your ice cream machine until it freezes to a soft frozen state, about 20 to 25 minutes. Put in the freezer to continue to firm up until you are ready to serve.