Place ingredients, including optional ingredients if using, into a blender and puree until smooth. Add a little more baking soda, if needed, to achieve a bluer color.
Pour into two standard, 16-well ice cube trays. Rap a few times on the counter to help release any bubbles. Freeze for several hours, preferably overnight, until firm.
Pop frozen smoothie cubes out of trays, then transfer to a freezer proof, airtight container.
To use add 4 cubes per serving to your favorite smoothie recipe to replace 1/2 cup fruit. Or, blend 8 cubes per serving, plus enough water or coconut water, for use as a quick way to replenish electrolytes.
Nutrition info includes the optional ingredients.
The butterfly pea powder adds the blue color, without any other additions, the cubes will be light cream in color. Any superfood juice powder can be used to create other beautiful colors.