Combine the horchata powder and liquid: Empty the powder from the package into a large pitcher or blender. Carefully pour in the 4 cups cold milk or water.

Blend thoroughly: Mix on low speed for 30 seconds, then high speed for 1 minute until completely smooth with no lumps. For the creamiest texture, use a high powered blender.

Taste and adjust sweetness if desired: Depending on your horchata powder, you may want to add sugar, honey, or maple syrup to suit your preferences. Stir again after adding.

Refrigerate for at least 2 hours: Chilling allows the flavors to develop fully. Overnight is ideal.

Give a final stir before serving over ice. Top each glass with a sprinkle of cinnamon. Enjoy!