The CWI Cookbook

 Several stalks of rhubarb
Brown sugar
Premade tart shells or pie crusts
Granulated white sugar

Take the young green stalks of the rhubarb plant, or spring fruit as it is called in England; and having peeled off the thin skin, cut the stalks into small pieces about an inch long, and put them into a sauce-pan with plenty of brown sugar, and its own juice. Cover it, and let it stew slowly till it is soft enough to mash to a marmalade. Then set it away to cool. Have ready some fresh baked shells; fill them with the stewed rhubarb, and grate white sugar over the top.
For covered pies, cut the rhubarb very small; mix a great deal of sugar with it, and put it in raw. Bake the pies about three quarters of an hour.

Miss Leslie’s Directions for Cookery by Eliza Leslie, 1851

Comments: Instructions to use “granulated white sugar” seem redundant today, when that’s pretty much the only way that sugar is commonly sold. In the 19th century things were different. Sugar was produced at the cane-refining mills in molds shaped like cones to make the end product easy to remove. The sugar cones were then wrapped in paper and shipped to market without further processing. Grocers would upon request break off a chunk of smaller size, since few people could either afford a whole cone or had (ant-proof!) ways to store it at home. In either case the cook was often called upon to get the amount needed for an individual recipe from the chunk by means of a hammer and chisel, and then scrape it over a grater to the desired fineness. Brown sugar, since it still contained much of the molasses that had been refined out of the white sugar, was often softer and easier to work with.