Combine the brown sugar, cream, butter, vanilla, and salt in a medium saucepan and set over low heat.
Bring to a simmer and cook, stirring constantly, until the mixture is uniform and begins to thicken, about 8 minutes. It will still appear thin but should coat the back of a spoon.
Remove from the heat and let cool. The mixture will thicken more as it cools.
Store in the fridge or cooler until you're ready to serve.
Just before serving, pour or scoop the butterscotch sauce into a 6-inch cast iron skillet. Set it over low heat on a camp stove or stovetop, or over warm coals on a campfire and heat gently until just warmed through, stirring occasionally.
Top with almonds and serve with apple wedges for dipping.
Notes
Scaling the recipe--To make enough to feed 8 to 10 people, double the recipe and serve it in a 10-inch skillet.
Storage--Store the caramel in a sealed jar or container in your fridge or cooler for up to 1 week.
Thinning the sauce--The sauce will thin as it's warmed, but if it's still too thick for dipping, stir in a tablespoon of cream to loosen it.
Dietary--This recipe is suitable for gluten-free diets.