Cookie joined the 7th Michigan Cavalry Brigade under General McLellan in 1861. He began work as a teamster and mule skinner. He was later recruited as a sharpshooter by 2nd Lieutenant Colonel George A. Custer. 3rd Division, Cavalry Corps, Army of the Potomac in 1863 under General Pleasanton. He distinguished himself as "Expert Marksman" at Battle of Chancellorsville, he was promoted to corporal. After spending a hungry week without supplies, Farnsworth took it upon himself to begin training as a field scout and cook. He showed remarkable aptitude as quartermaster but preferred the kitchen. He said, "...it bein my true art an all." He followed the newly promoted Brigadier General Custer to the Michigan Cavalry brigade. He saw action at Gettysburg, Bristoe, and Mine Run. Once again He was pressed into service as a sharpshooter. Farnsworth is credited with shooting Confederate General Pettigrew at Falling Waters in 1864. After the War between the States, Farnsworth followed the now demoted Lieutenant Colonel Custer as his personal chef to Fort Laramie in Wyoming.
In 1866 he was with the 7th United States Cavalry. He toured with Custer during the 1867 Sioux and Cheyenne Expedition. In May 1876, Farnsworth was blamed for a rash of food poisoning that struck the enter officers' corps and was demoted and transferred to the command of general cook at Fort Abercrombie in North Dakota.
Farnsworth left the Army in 1878 and moved to Houston, Texas, where he quickly rose to the position of Yard Boss of Whitmore Industries Stockyard and Feedlot. He attended culinary school in Baton Rouge and New Orleans. He moved to New York and opened Three Chestnut Restaurant, where he worked as Chef. He later sold his restaurant at a loss and took position as Chef for Waldorf Astoria Hotel. He was fired after an altercation with a complaining customer; when the customer complained about his food, he responded by shooting the customer in the leg.
Despite his advancing years, "Cookie" Farnsworth remains at the forefront in the area of field culinary preparation. Farnsworth earned a reputation while enlisted in the U.S. Army as a man who could literally feed legions with almost no supplies at all. Renowned for his ability to find food or supplies where there are seemingly none, regardless of season, climate, or geography. Reputed to have prepared lavish dinner for General Sheridan during Appomattox, that centered around a dish said to be rabbit amadine but was in reality tomcat and boot soles. He said, "I heard about this'n from a Frenchman down Louisiana way." He is experienced with livestock, quarter mastering, backing, and fur trapping. He also did a brief stint as a buffalo hunter in 1877.
- Cookie has a tattoo of the United States on his chest.
- He's a terrible cook. While humans find his meals disgusting, lava dogs will eat them.
- Jim Varney died before the final cut of the film, so his replacement for the sequel, Steve Barr, finished his recordings, but Varney is still credited.