Heat a large saucepan over medium heat and add the rice and almonds together. Stir constantly for 3 to 4 minutes until you smell a toasted, nutty aroma and the rice and almonds turn slightly golden.

Pour 4 cups of water into the saucepan with the toasted rice and almonds. Add the cinnamon, cloves, and salt, then stir to combine everything evenly.

Bring the mixture to a rolling boil, then immediately reduce heat to low and remove from heat. Let it cool slightly.

Cover the saucepan and let it sit at room temperature for at least 4 hours, or overnight in the refrigerator for deeper flavor.

Set a fine mesh strainer over a large bowl or pitcher and carefully pour the steeped mixture through. Let it drain completely, pressing gently on the solids with the back of a spoon to extract all the liquid.

Pour the strained liquid into a high-powered blender in batches if needed. Add the remaining 2 cups of water, sugar, and vanilla extract, then blend on high speed for 60 to 90 seconds until completely smooth and frothy.

Pour the blended horchata through a fine mesh strainer lined with cheesecloth into a clean pitcher or storage container for the smoothest texture.

Stir in the rum or liqueur of your choice and mix thoroughly. Refrigerate for at least 30 minutes before serving.

Pour the chilled spiked horchata into glasses filled with ice. Stir gently before serving and enjoy immediately.