From the Walgreens web site...
The milkshake that shook up America
By 1920, now 20 stores strong and growing quickly, Walgreens was an established fixture on Chicago's retail scene. Throughout this decade, Walgreens underwent phenomenal growth. By 1929, the total number of Walgreens stores reached 525, including locations in New York City, Florida and other major markets. Many factors contributed to this unprecedented growth: a superb management team, modern merchandising, innovative store design, fair pricing, outstanding customer service and exceedingly high pharmacy quality and service. Yet, one can't overlook something that may have seemed a minor innovation at the time. This was the invention of Walgreens immortal malted milkshake, an instant classic, by Ivar "Pop" Coulson in 1922. Coulson was a lover of fountain creations and the backbone the Walgreens soda fountain since 1914. His chocolate malted milk was a development for the company that was anything but minor.
Coulson had always been eager to improve on whatever he and his fountain clerks had to offer, and he made generous use of Walgreens extra-rich ice cream, manufactured in Walgreen's own plant on East 40th Street in Chicago.
Until then, malted milk drinks were made by mixing milk, chocolate syrup and a spoonful of malt powder in a metal container, then pouring the mixture into a glass. On one especially hot summer day in 1922, Pop Coulson set off his revolution. To the basic mixture, he added a generous scoop of vanilla ice cream, then another.
Old Fashioned Chocolate Malted Milk
1. Use a Frosted Malt Can
2. 1 1/2 oz. Chocolate Syrup
3. 3 - #16 Dips of Vanilla Ice Cream
4. 5 1/2 oz. of Cold Milk
5. Add Malt Powder (One Heaping Tablespoonful)
6. Place On Mixer Only Until Mixed - Do Not Over Mix
7. Use a Generous Portion of Whipped Topping In A #1808 - 10 oz. Glass
8. Pour Malted Milk in Glass Approximately 2/3 Full
9. Serve Remainder Of Malted In A Shaker Along With The Glass To The Guest With Straws and Package of Fountain Treat Cookies
Priced at 20 Cents,
Coulson's new malted came with a glassine bag containing two complimentary vanilla cookies from the company bakery.
Response could not have been stronger if Coulson had found a cure for the common cold! His luscious creation was adopted by fountain managers in every Walgreens store. It was written about in newspapers and talked about in every city where there was a Walgreens. But most of all, it was the object of much adoration. It was not at all unusual to see long lines outside Walgreens stores and customers stand three and four deep at the fountain waiting for the new drink. Suddenly, "Meet me at Walgreens for a shake and a sandwich" became bywords as popular as "Meet me under the Marshall Fields clock" at State and Randolph in Chicago.
So, once again, Charles Walgreen's prediction that his soda fountain would be absolutely essential to his stores as a source of revenue, company growth and increased customer satisfaction (which translated into even higher levels of customer loyalty and patronage) came true. In its own way, Coulson's malted was the fuel for Walgreens dramatic growth.