Here is an interesting recipe from the Southern Planter, June 1859, p. 338:
FRENCH HONEY--One pound of white sugar[;] six eggs leaving out whites of two; the juice of three or four lemons, and the grated rinds of two, and a quarter of a pound of butter. Stir over a slow fire until it is about the consistency of honey.
Under the heading "Receipts from a Lady," this article was apparently republished from another source because it began with this introduction:
A lady friend has sent us the following receipts for making lemon pies and French honey, which we publish with great pleasure in the Telegraph.
(The Telegraph's place of publication is not given).
The article included a recipe for lemon pie, but it isn't clear if French honey was supposed to be served on or with the pie. French honey was clearly a topping, probably for bread, toast, and pastries, and perhaps also for cakes and puddings.
The above links go to a digitized version of the Southern Planter, available through the Hathi Trust. If you would like to review the original print version, please request an appointment to see it using the Special Collections online form (please provide us with the call number: S1 .S6 v.19(1859).)