My sources for this are many Google searches about butterscotch on the internet.
First, there is no such thing as "true butterscotch". The many recipes I found have various
ratios of sugar to butter, and there is a variation in the ingredients. So there is only
"version A" of butterscotch, "version B", "version C" and so on. The commonality
among most of them is that they contain sugar, butter, salt, and molasses. The sugar
can be light brown sugar, dark brown sugar, or just plain sugar. If it's just plain sugar,
molasses is added to the recipe; otherwise, molasses is optional. If molasses is added
it can be plain molasses or, occasionally, blackstrap molasses. The sugar to butter
ratio varies greatly — anywhere from 4:3 to 16:1 by weight, I've read.
The sugar, butter, salt, and molasses are mixed together and cooked until the temperature
is raised to anywhere between 245 degrees F to 310 degrees F.
One question I asked myself is why, if molasses is just mostly caramelized sugar (as many
sources on the internet say), why, if it's added separately, is it always cooked along with the
other ingredients and not added later? After further research on the internet, I found the
answer: Molasses is NOT caramelized sugar! Why? To refine sugar, sugar cane is boiled in
a vacuum at 160 degrees F. 160 degrees F is well below the caramelization temperature of
sugar, which begins at about 320 degrees F. Also at 160 degrees F the Maillard reaction
(which I'll get to shortly) is very slow, so molasses has undergone very little Maillard reaction.
Caramelization is not important for butterscotch because butterscotch is not caramelized, but
the Maillard reaction is very important since it is what develops the butterscotch flavor. The
Maillard reaction takes place at an optimal rate between 270 and 310 degrees F. To avoid
caramelization from occurring, among all but one of the recipes I've seen for butterscotch,
the maximum cooking temperature is 300 degees F.
How to Make Butterscotch Flavor Powder
I like the flavor of butterscotch a lot, and after some experimenting I figured out how to
make a butterscotch flavor powder that I could add to other things, such as yogurt. The
following recipe is based on recipes for butterscotch I've found on the internet, plus a
couple of my own ideas, which seem to be original.
60 grams dark brown sugar
30 grams unsalted butter
1/8 tsp salt (not sea salt)
1 1/2 Tbsp blackstrap molasses (optional, to make the flavor "extra butterscotchy")
2 tsp water (approximarely)
Mix the ingredients together in a pan, adding just enough water to wet down the
other ingredients, set a stovetop burner in the medium heat range, and, stirring
constantly, cook slowly until the temperature of the mixture is a carefully measured
310 to 315 degrees F. Cooking slowly is important for giving the Maillard reaction time
to take place. (The Maillard reaction is what develops the butterscotch flavor.) For
measuring the temperature, I use an infrared surface temperature thermometer.
There are many brands of these infrared thermometers on Amazon.
When the mixture is cooked, pour it immediately (not letting it harden) onto a flat
surface that has been covered with a sheet of parchment paper, and let the mixture
cool for, say, 20 minutes, until it is rock solid. Then crack it up with your food-gloved
hands, transfer it to a blade type coffee grinder, and grind it into a fine powder. This
may require several "transfer-grind" operations. Store the powder in a refrigerator,
and use it as desired. When using the powder, also add some vanilla flavor or extract.
Serving size 1 Tbsp. Makes about 7 servings.