Use this decadent sauce in Jimmy Fallon's Late Night Snack Ice Cream Cake.
In a medium saucepan, mix together sugar, corn syrup, and 1/4 cup water until sugar is moistened. Place over medium-high heat and bring to a boil, brushing down sides of pan with a pastry brush that has been dipped in water, until deep amber in color.
Gently swirl saucepan to ensure sugar mixture is well combined. Remove from heat and carefully add heavy cream; mixture will bubble. Stir in creme fraiche and salt. Transfer sauce to a glass container and let cool at room temperature until thickened, 1 to 2 hours.