In a small bowl, soak almonds, cashews, and dates in water. Be sure that the water is covering all the nuts and dates. Let sit for 8-12 hours.
Once they're done soaking, drain the nuts and the dates and rinse with clean water.
Place in a high-speed blender with 2 1/2 cups of water and blend for about a minute or two until everything is as smooth as possible.
Pour mixture into a nut bag that's placed over a bowl or pitcher. Squeeze out all the liquid, reserving the remaining nut meal to use in recipes such as muffins, cookies, and quick-breads.
Pour the drained liquid back into the blender, add extract, agave, cocoa powder, and salt, and blend on medium speed until completely combined.
Refrigerate in a pitcher or glass jar. Will keep for about 5-7 days stored in the refrigerator.