Place the vanilla ice cream, ice cubes, and optional syrup into a blender.
Secure the lid and start blending on a low setting, gradually increasing to high until the mixture becomes thick, smooth, and icy, about 30-45 seconds.
Stop the blender and check the texture; it should be creamy yet wintry, with tiny ice crystals evenly dispersed.
Pour the slushie into chilled glasses, allowing the icy frost to cling to the sides for a frosty presentation.
If desired, drizzle a little extra syrup on top or garnish with a sprig of fresh herbs or a twist of lemon for extra flair.
Serve immediately with a straw or spoon and enjoy the icy, vanilla-scented refreshment.