Prepare the Irish Cream whipped cream by mixing together the heavy cream and 1/4 cup Irish Cream syrup on high in a chilled mixing bowl until creamy and fluffy. Chill until ready to serve.
In a small bowl mix together chocolate syrup and remaining 1/2 tsp Irish Cream syrup.
Drizzle the inside of a large chilled milkshake glass with flavored chocolate syrup.
Add milk and pistachio ice cream to a blender and blend until smooth.
Pour into the glass.
Top with Irish Cream whipped cream, drizzle on more chocolate syrup and add green sprinkles and a straw.