In a saucepan, add sugar, water and corn syrup and bring to a boil over medium-high heat, without stirring. Cook until it turns a slightly yellow straw color, about 8 minutes. Reduce the heat to medium-low and continue to cook until it turns an amber color about 5 minutes. A thermometer should read 350º. You can swirl the pan but avoid stirring.

Remove from the heat and stir in cream, vanilla and salt. It will sizzle. Stir until it is smooth. Pour into a glass bowl to cool. This makes 2 cups so you will have extra.

Butter a 9 x 13 pan.

Melt the butter in a saucepan over medium heat. Cook until it begins to brown, about 2 minutes. Immediately add the marshmallows, whisking until smooth.

Remove from the heat and add vanilla, salt and ½ cup of caramel sauce, whisk until combined. Add Rice Krispies, stirring quickly to coat the cereal. Place in the prepared pan and flatten it into the pan. Let it cool to room temperature.

If desired, drizzle caramel over the cooled Rice Krispie bars.