Maple syrup
Ingredients needed are some kind of liquor to use as a base, usually rye whiskey. The only other ingredient needed to make maple liqueur is pure maple syrup. Table syrup cannot be used as it is often made with high fructose corn syrup and artificial flavouring instead of real maple. Maple syrup comes in various different grades, and the grade of a syrup is determined by its colour, clarity, density, and how strong the maple flavour is. As the sap harvesting season progresses, the maple syrup that is produced becomes darker and more caramel in colour. These darker syrups also tend to have the most intense maple flavour, compared to the lighter taste one would get from syrup produced early in the season. Darker syrups create a more intense maple flavour in the liqueur as well and because of this are often preferred when producing maple liqueur. The darker the syrup that is used, the more intense and full bodied the resulting liqueur will taste.