A surprisingly large percentage of sweets and desserts rely on a small handful of flavors, most notably, vanilla, chocolate and caramel. Vanilla and chocolate are natural flavors, drawn from the seeds of tropical plants. Caramel is different, created from the relatively bland sweetness of sugar. Caramel sauces usually call for a portion of heavy cream, which gives the caramel a light color and distinctive richness. Cream isn't an essential part of the equation, though, and good caramel can be made without it.
Caramel and Complexity
Caramel is made by heating sugar until it browns naturally, which takes place at about 340 degrees Fahrenheit when you're using conventional granulated sugar. The heat breaks up the simple sugar molecules, creating small chemical fragments that re-combine in random and complex ways. This process creates hundreds of new flavor compounds, each reducing the sugar's sweetness but contributing to the distinctive combination of flavors that makes caramel so interesting. If the sugar is left to cool, it crystallizes and becomes hard, which limits its uses. Cream is typically added to make dessert sauces, but it isn't mandatory.
The lowest-calorie alternative to a cream-based caramel sauce is a water-based sauce. These are widely used in high-end restaurants and pastry shops since they provide a beautifully clear sauce that doesn't mute the innate complexity of the caramel flavor. The caramel's thickness can be manipulated by increasing or decreasing the amount of water until it reaches the right consistency. Clear caramel typically has the thickness of corn syrup, which gives it a texture that enables it to cling to a dessert. It's also used undiluted to make a clean, hard glaze for cream puffs, or it can be spun, drizzled or pulled to make professional-looking dessert garnishes.
Although butter is made from cream and has roughly the same make components, it creates a different texture when it's added to caramel. Butter caramel retains the deep brown of clear caramel, distinctively different from the pale gold of cream-based caramel, but has a flavor that's just as rich. Depending how much butter you add, it can be either a thick sauce or a crunchy, brittle candy. The candy is often broken into shards or coarse crumbs, then coated in chocolate or used as an ingredient in cakes or cake fillings.
If your goal is to replace a cream-based caramel sauce with something that tastes similar but contains fewer calories, you'll achieve the best results if you use evaporated milk. Ordinary milk and even light cream can't handle the heat of caramelized sugar and will quickly produce grainy clumps of curdled milk proteins. Evaporated milk is concentrated enough to curdle, producing a light and attractive sauce that looks the same as a cream-based caramel. The distinctively "cooked" flavor of evaporated milk isn't a problem in caramel sauces, where it complements the rich flavors of the cooked sugar.