Roast the sweet potato in a 350 degree over for about 1 hour, or until soft. Remove from oven and set aside to cool. When cool mash until smooth.
Combine the brown sugar, salt, milk and heavy cream in a sauce pan. Heat over low-medium heat until sugar is melted.
Place the egg yolks in a bowl and wisk them together. Slowly wisk a small amount of the creamed mixture into eggs to temper them. Add the egg mixture to the sauce pan with the rest of the cream mixture and heat through for about a minute.
Remove the pan from the heat and wisk in the mashed sweet potato and the cinnamon.
Transfer mixture to a clean bowl and place in refrigerator for at least 2 hours to cool.
Place the sugar and graham crackers in food processor and pulse till lareg crumbs are formed. Add melted butter and pecans and pulse till combined. Set aside.
When the ice cream mixture is chilled enough, pour into an electric ice cream maker and let it churn for 30 minutes. Then add the graham cracker mixture and churn for 5 additional minutes.
Remove the ice cream from the ice cream maker to a container and freeze until desired consistancy.