Which ingredient is not used in the formulation of a Strawberry Shake?

In a Strawberry Shake, the primary ingredients typically include vanilla ice cream, milk, and strawberry puree to create a creamy, fruity beverage. Vanilla ice cream serves as the base, providing sweetness and texture, while milk ensures the shake has the right consistency. Strawberry puree contributes the flavor and color that defines the drink.

Chocolate syrup, while a popular topping for various desserts and shakes, is not a standard ingredient in a strawberry shake. Including it would alter the intended flavor profile of a strawberry shake, which focuses on strawberry and cream flavors. Therefore, chocolate syrup is not part of the fundamental formulation for a traditional Strawberry Shake.