Place the blueberries, basil leaves, ice cubes, and honey (if using) into the blender.
Secure the lid tightly and blend on high speed until the mixture is smooth and the ice is finely crushed, about 30-45 seconds. You should see a vibrant purple-blue color and a chilly fog escaping from the blender.
Stop the blender and check the texture—if it's too thick, add a splash of water or more ice and blend briefly to loosen it up. If you prefer it thicker, add a few more ice cubes and blend again.
Pour the slushie mixture into tall glasses, allowing the colorful swirl of berries and herbs to flow freely.
Garnish each glass with a small basil leaf or a few blueberries for an inviting presentation.
Serve immediately with a straw and enjoy the crisp, aromatic burst of flavor with every sip.
