As for what is in the concoction, the original Shamrock Shake is basically vanilla ice cream, mint flavored syrup, and whipped cream. However, the recent Oreo Shamrock McFlurry introduces one crucial ingredient: Oreo cookie pieces.

The Shamrock Shake is officially back in season on Monday, Feb. 20, 2023, at McDonald's along with the Oreo Shamrock McFlurry.

1. The Shamrock Shake was created in 1967 by Hal Rosen, a Connecticut McDonald's Owner/Operator who made the delicious, mint shake in celebration of St. Patrick's Day. It later debuted in select locations across the U.S. in 1970 and was an instant success.

Initially, the shake was lemon/lime flavored with vanilla ice cream, lemon/lime sherbet, and vanilla syrup. By 1973, the shake was merely a green colored vanilla shake, eliminating the lemon/lime sherbet. It is now mint flavored.

The First Shamrock Shake The celebrated drink got its start as the “St. Patrick's Day Green Milkshake,” created in 1967 by Connecticut McDonald's owner and operator, Hal Rosen. It wasn't until three years later in 1970 that corporate made the decision to debut the “Shamrock Shake” in select locations across the US.

The Shamrock Shake® was created in 1967 by Hal Rosen, a Connecticut McDonald's Owner and Operator who made the delicious, mint shake in celebration of St. Patrick's Day. It debuted nationally in 1970 and was an instant success across the country.

McDonald's doesn't actually sell milkshakes and hasn't in a long time -- at least 35 years, when I was working there in high school. On the menu they're listed as "shakes," because they don't contain enough milk. Just some food -- or faux food -- for thought.

Saint Patrick, one of Ireland's patron saints, is said to have used it as a metaphor for the Christian Holy Trinity. The name shamrock comes from Irish seamróg ([ˈʃamˠɾˠoːɡ]), which is the diminutive of the Irish word seamair and simply means "young clover".

The three-leaf clover, a type of trefoil plant, has been considered the unofficial national flower of Ireland for centuries. Irish legend says that Saint Patrick used the shamrock as an educational symbol to explain the Holy Trinity to nonbelievers as he converted the Irish to Christianity in the fourth century.

The Shamrock Shake didn't taste any different than it had in the past. It's a vanilla shake with mint syrup mixed in, making it taste like a minty vanilla shake. This is what happens when you use vanilla as a base - we learned this the hard way with Wendy's strawberry and peppermint Frosty releases.

According to the home of the Hamburglar, the Shamrock Shake was created in 1967 by Hal Rosen, a franchise owner in Connecticut who made the mint shake in celebration of St. Patrick's Day.

While trying to convert the Irish into Christians, St. Patrick used the shamrock to explain the holy trinity with each leaf representing the Father, Son and Holy Spirit. The three leaves of a shamrock are also said to stand for faith, hope and love. A fourth leaf is where we get the luck from.