Preheat the oven to 350˚. Butter a 9-inch springform pan. Pulse the graham crackers in a food processor to make fine crumbs. Add the sugar and melted butter and pulse until the mixture looks like wet sand. Press evenly into the bottom of the springform pan and 1 inch up the sides. Bake until golden brown and set, 10 to 12 minutes. Let cool.

Reduce the oven temperature to 325˚. Beat the cream cheese in a large bowl with a mixer on medium speed until smooth. Add the sugar and salt and beat until light and fluffy. Add the eggs one at a time, making sure each is incorporated fully before adding the next. Beat in the maple syrup, sour cream and vanilla until the mixture is smooth.

Tightly wrap the bottom and sides of the springform pan with a double layer of foil, covering up to the rim (this is so water does not seep in). Pour the cream cheese filling into the pan and smooth with a spatula.

Place the cheesecake in a roasting pan and place in the oven. Pour enough boiling water into the roasting pan to come halfway up the sides of the springform pan. Bake until the cheesecake is golden brown but still slightly wobbly in the center, about 2 hours.

Carefully remove the springform pan from the roasting pan. Let cool for 15 minutes. Remove the foil and run a paring knife around the sides of the pan to loosen the cheesecake. Refrigerate the cheesecake until cold and firm, at least 6 hours or overnight.

Pour the maple syrup into a medium saucepan fitted with a candy thermometer and bring to a boil over high heat; cook until the thermometer reads 225˚, about 5 minutes. Remove from the heat and stir in the butter and heavy cream just until blended. Unmold the cheesecake and serve with the maple sauce.