Blend blackberries and blueberries: Add 1 cup of blackberries and 1 cup of blueberries in a blender, let them blend uniformly and pour into a glass jar.
Blend coconut base milk and vanilla: Add 1 cup to blend until the mixture is smooth and slushy.
Blend sweetener and ice- Blend your sweetener and ice until it mixes uniformly.
Serve and garnish: Mix them in a tall glass and drizzle chocolate syrup on top, and your drink is ready to go.