Hill and Parloa weren't actually a single author, but rather two separate contributors to a cookbook titled "Chocolate and Cocoa Recipes" ([Amazon chocolate and cocoa recipes parloa and hill]).
Maria Parloa (1843-1909) was the author of the "Chocolate and Cocoa Recipes" section of the book. She was a well-known home economist and culinary authority in the late 19th and early 20th centuries.
Janet McKenzie Hill (1852-1933) contributed the "Home Made Candy Recipes" section.
The book itself was a promotional piece commissioned by the Walter Baker Chocolate Company in 1909. It featured recipes using their cocoa products, ranging from simple drinks to elaborate desserts.
While not a traditional cookbook by a single author, "Chocolate and Cocoa Recipes" offers a glimpse into Victorian era sweets and treats, and the contributions of both Parloa and Hill to American culinary history.