Butterscotch syrup is a thick, liquid confection containing the flavors of brown sugar and butter. Traditional butterscotch is thicker and made with a mixture of brown sugar, butter, and cream heated to candy's "soft crack" stage. The syrup uses treacle or similar ingredients and is heated to a lower temperature for a soft, thin consistency. Often the brown sugar is cut or substituted with treacle, which is mixed with butter and cream before cooling. Basic butterscotch is known to have originated during the 19th century.
True butterscotch consists of a mixture of brown sugar, butter, and cream heated to a certain temperature range. The confection is similar to toffee but is only boiled to sugar's "soft crack stage" at about 270° to 290° Fahrenheit (132° to 143° Celsius). At this stage, its cooled threads are just pliable, not stiff and breakable like those of toffee.
The addition of treacle or other liquid inverts the sugar in this mixture to create butterscotch syrup. It is also heated only to the thread stage, about 230° to 233° Fahrenheit (110° to 111° Celsius) for a much softer, thinner confection. Homemade recipes may contain real butter and sugar, or, as is often the case in commercial products, artificial flavorings and high fructose corn syrup. While the thicker sauce is typically used as a garnish or topping, butterscotch syrup is used for flavoring, much like vanilla and other extracts. It's especially common in beverages, liqueurs, and as an ingredient for butterscotch-flavored candies and puddings.
Homemade butterscotch syrup can be made by cutting or replacing the brown sugar called for in a sauce recipe. Butter is heated in a pan on medium-low heat until melted, when the syrup and brown sugar are added. Replacing all of the brown sugar produces a thinner syrup, but this affects flavor. The mixture is stirred for two to four minutes, until the grainy mixture just smooths into a molten liquid. Cream is added and whisked in for about 10 more minutes, at which point the syrup is removed from heat and left to cool.
The earliest known version of the confection made an appearance in 1817 as "Doncaster Butterscotch" by S. Parkinson and Sons. The term "butterscotch" may refer to the scorching of its fatty ingredient, but, the word scotch also means "to cut," which is required while the confection is still soft, before hardening. Butterscotch syrup, however, is not cut due to its thinner consistency.