Prepare coffee first (or espresso shot) and mix it together with the plant based milk, vanilla and blue spirulina. The amount of spirulina depends on what colour you want to have. I used around ¼ tsp so very little to get that light blue.
Fill ice cubes into a sufficiently large glass and give 1 tsp marble syrup to it. Pour the blue spirulina milk over it and stir everything well. In the end, I added a dash of plant milk.