In a 4 quart saucepan, whisk 2 cups milk, heavy cream, corn syrup, sugar, and salt. Set over medium heat. Watch closely and whisk often.
Whisk together the cornstarch and reserved 2 tablespoons milk until smooth. Then set by the saucepan.
As the mixture comes to a low boil, whisk to ensure all the sugar is dissolving. Allow to boil slowly for 2 minutes. Remove from heat and whisk in the cornstarch mixture. Return to heat and whisk until the ice cream is bubbling throughout.
Remove from heat and stir in the vanilla extract and instant coffee granules. Stir until the coffee has dissolved.
Let cool to room temperature, about 20 minutes. Then pour into an airtight container through a strainer just in case there are any lumps.
Chill for at least 6 hours.
While chilling, make the caramel sauce. A favorite store-bought variety can also be used.
When the ice cream base has chilled, remove it from the refrigerator and pour it into the ice cream maker.
Follow the instructions with your maker as they can vary depending on the manufacturer. Insert the paddle and churn until thick. In a KitchenAid ice cream attachment, this takes about 25-30 minutes.
When the ice cream has churned, scoop into an airtight freezer container, layering the ice cream with the prepared caramel.
Freeze 4-6 hours before enjoying to ensure it is at a good scooping consistency.
For the caramel sauce
Combine the sugar and corn syrup in an 8-inch skillet or shallow saucepan.
Melt slowly over medium heat. As the edges begin to melt and turn amber in color, scrape to the center of the skillet.
When all the sugar is melted and is a deep amber color, remove it from the heat.
Drizzle in heavy cream, 2 tablespoons at a time, stirring after each addition until the caramel is smooth. If the cream seizes and creates hard caramel pieces, gently stir over low heat until smooth.
When all the cream is added and the caramel is smooth, add the butter, vanilla, and salt. Stir until the butter is melted.
Cool to room temperature and refrigerate in an airtight container until ready to use. This will store up to 3 weeks.