A thick, Chocolate and Hazelnut flavored Caramel Sauce that can be used as a Ganache, Glaze or warmed as a sauce. Works just as well for the layers of a Cake as it does as a topping for a Ice Cream Sundae!
Combine the Sugar, Water and Corn Syrup (or Glucose) in a large pot over medium-high heat. Brush the sides of the pot with a wet pastry brush to remove any stray Sugar granules.
Chef's Note: Once the pot is on the heat, do not stir. Stirring can cause the Sugar mixture to recrystallize. Make sure your pot can hold at least three times the volume of your ingredients. Later, when you add the Cream, the mixture will bubble dramatically. If the pot is too small, the Caramel will spill everywhere.
Make a slurry (i.e. a paste) with the Cream and Cocoa Powder, slowly adding the Cream to the Cocoa Powder while stirring gently.
Slowly adding the Cream to the Cocoa Powder while stirring helps to create a smoother mixture without leaving dry lumps of Cocoa Powder.
Continue heating the Sugar until the mixture begins to turn a golden amber. At this point, it is okay to stir gently to redistribute the heat if necessary. Continue heating the Caramel until it turns a deep amber or to approximately 360 - 370 degrees Fahrenheit (182 - 188 degrees Celsius).
Chef's Note: As the Caramel continues to cook, the rate at which the temperature rises will increase. Keep an eye on your heat and be ready to remove the pot from the stove as you approach your desired color. Remember that the Caramel will continue to cook even after the pot is removed from the heat.
When the Caramel has reached temperature, remove the pot from the heat and slowly pour in the Cream and Cocoa Powder mixture while whisking actively. Do not pour too much of the mixture in at one time. The mixture will steam and bubble dramatically, and the pot could overflow.
Once all of the Cream and Cocoa Powder mixture has been incorporated, add the Salt and Butter, and stir until combined. When the Butter is fully incorporated, add the Nutella and stir until combined.
Set the Nutella Chocolate Caramel Sauce aside to cool and thicken, stirring occasionally.
Store the Nutella Chocolate Caramel Sauce in an airtight container in the refrigerator for up to a month or in the freezer for several months. The cold Nutella Chocolate Caramel Sauce is very thick. To return it to a pouring consistency, gently heat it over a double boiler.