Over medium heat, combine half-and-half and heavy cream until bubbles appear along edge of pan.
Whisk together egg yolks, sugar, maple syrup and spices until thick and smooth. Pour 1/2 cup of hot cream into egg mixture and whisk. While whisking, pour egg mixture into hot milk and cook over medium heat for 6 minutes.
Remove from heat and let cool to room temperature. Stir in pumpkin puree and crystallized ginger. Cover and chill for 1 hour.
Pour mixture into ice cream maker and freeze according to manufacturer's instructions.