In a small saucepan combine the brown sugar and cornstarch. Add apple cider and butter. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 2 minutes more. Remove from heat.
Gradually stir 1/2 cup of the hot brown sugar mixture into beaten egg yolk. Add the egg mixture to the saucepan. Cook and stir until bubbly; reduce heat. Cook and stir for 2 minutes more. Remove from heat; cover and cool.
In a bowl beat the cream cheese until fluffy. Gradually beat in 1/2 cup of caramel sauce. Cover and chill remaining sauce for up to five days. Serve over apple slices, ice cream, or poached fruit. Makes 3/4 cup.