Use a 4 qt slow cooker. Combine the milk, sugar and tapioca in the insert. Stir well to mix.
Cover and cook on High for two to three hours. It will still be soupy at this point.
In a medium or large mixing bowl, whisk together the eggs, almond extract, and cocoa powder.
Remove 1/2 cup of the hot tapioca/milk mix from the crockpot, and stir into the eggs, whisking all the time. A standard ladle is 1/2 cup. Add another 1/2 cup of the hot mix, whisk thoroughly, and then another 1/2 cup. This tempers the eggs, so that they don't turn into scrambled eggs.
Pour the egg mixture into the slow cooker and stir very thoroughly to combine.
Cover and cook on High for 30 minutes to one hour, or until the tapioca has begun to swell and thicken.
Turn off the slow cooker, remove the lid and let this stand an hour to thicken further. Remove to a large bowl, cover with plastic pushing the plastic against the tapioca (to prevent a skin from forming), and chill.
Note1: I used seed tapioca, about the size of sesame seeds. I will try this using a couple of tablespoons less, to get a slightly looser consistency, although it was just fine the way it was.
Note2: I used 2% milk, as that was what I had. I also used only 3/4 cup sugar - the original recipe calls for 1 1/2 cups, and that would have been much too sweet for me. I might double the amount of cocoa powder next time.