Add both the sugar and water into your Instant Pot and stir. Press the "Saute" button. Continue stirring the water as it heats.
The Saute function on an Instant Pot takes the temperature up to 160 ~ 176°C (320 ~ 349°F), which is the temperature you need to caramelize the sugar.As the mixture heats, the sugar will clump but then it's going to melt into a more amber colored liquid. Don't let it burn by sitting, and keep stirring.Do this until you recognize that the sugar water has thickened, or caramelized. It takes about 10 - 15 minutes.
Once caramelized, turn off the Instant Pot. Add the heavy cream and whisk until combined.Continue stirring, and if you notice any clumping, continue stirring. You might have to stir more vigorously or use a whisk in this step.
Add butter and salt, keep whisking until fully combined. Let cool to thicken. Pour into a jar.
Notes
Step 3: If you notice any clumps, they will melt, or you can stir them out. The sauce is going to thicken as it cools.In this recipe I recommend a thermometer, but you don't really need one. You can visually observe when the sauce is thickening. I just provide the temp for those who like to use one!I wouldn't use a funnel or anything else to pour the sauce into the containers. Everything you cover with caramel sauce is going to end up sticky. Just do the best you can and have a sponge at the ready.If you're going to gift that day you can go ahead and leave it out. Otherwise, store in the fridge for up to a month. You can also freeze in an airtight container for up to three months. You'll want to thaw before using.