Add the blackberries, banana slices, Greek yogurt, almond milk, honey, and vanilla extract to a high-speed blender.
Blend on medium speed for 30 seconds until the ingredients are well combined and the mixture is smooth.
Add the ice cubes to the blender and pulse on high speed for an additional 20-30 seconds until the ice is fully crushed and the smoothie is thick and creamy.
Pour the smoothie into two glasses and serve immediately, optionally garnishing with a few extra blackberries on top.