The Shamrock Shake® and OREO® Shamrock McFlurry® made their big return to participating McDonald's restaurants nationwide in the US and in Ireland too until after March 17.

McDonald's says its classic Shamrock Shake® is made with creamy vanilla soft serve, blended with mint syrup, and topped with a sweet, whipped topping, while the fan-favorite OREO® Shamrock McFlurry®, comes blended with crushed OREO® cookies.

The history of the McDonald's Shamrock Shake

It may be a firm favorite treat around March 17, but did you know Shamrock Shakes were originally invented to raise money for charity?

The Shamrock Shake was developed in 1970, according to McDonald's. However, according to a 2011 report on Delish.com, Harold Rosen, who owned a McDonald's in Connecticut, claims he invented the popular holiday drink in 1966.

The McDonald's website says: "It all began with a little girl, a football team, and a visionary doctor."

The Philadelphia Eagles tight end Fred Hill's daughter was diagnosed with leukemia and began treatment. The Hill family was camping out in waiting rooms in hospitals and saw other families doing the same. They realized that many families who were traveling long distances to visit their sick family members had nowhere to stay and could not afford hotel rooms. The Hill family did something about it.

Hill and his team decided to raise some funds. The team's general manager, Jim Murray, called a friend in McDonald's advertising and suggested the team on the next promotional push. It just happened to be St. Patrick's Day.

Rogers Merchandising in Chicago created the shake and James Byrne, the executive artist at the firm, used a family recipe.

The Shamrock Shake raised enough money to buy a four-story house which was the first Ronald McDonald House

The Ronald McDonald House programs have exploded in size as a much-needed resource for families dealing with the difficulties of looking after a sick child in the hospital. It now has a presence in 60 countries and regions across the globe providing homes, family rooms, care mobiles, grants, and scholarships that help almost 6 million families. 

Kim Hill, the girl who inspired it all, unfortunately, passed away in 2011 aged 44.