Rinse the rice thoroughly under cold water until the water runs mostly clear. Transfer to a bowl, add the cinnamon stick and the warm water. Cover and refrigerate for at least 4 hours, preferably overnight. This step is non-negotiable. Short soak = thin, hollow horchata.
Remove most of the cinnamon stick, leaving a few small pieces with the rice. Add the finely chopped or grated dark chocolate directly to the soaking mixture. The chocolate must be extremely fine — chunks will not integrate later.
Blend in two batches for proper texture. Add half of the rice, soaking water, cinnamon pieces, and chocolate to a blender. Blend on high for a full 4 minutes, until very smooth and milky. Repeat with the remaining half. If you stop early, grit will survive. That’s unacceptable.
Strain the blended mixture through a very fine sieve or cheesecloth into a pitcher. Press firmly on the solids to extract as much liquid as possible. Discard the solids. This step defines the drink. Skip it and you’ve made rice sludge.
Stir in the evaporated milk, sweetened condensed milk, vanilla extract, and the pinch of fine sea salt. Add 2 cups cold water and stir until fully incorporated.
Taste and adjust deliberately, add sugar only if needed, and add more cold water if too thick. The final texture should be pourable, silky, and rich — not heavy.
Refrigerate for 1–2 hours until fully cold. Stir well before serving — light settling is normal.
Fill glasses with ice, pour over the chilled horchata, and garnish with ground cinnamon and an optional cinnamon stick.
