In a large bowl, rinse the millet couscous under cold water until the water runs clear. Drain.
Steam the couscous according to package instructions or place it in a heatproof bowl and pour boiling water over it until covered. Let it sit for about 10-15 minutes, then fluff with a fork.
In another large bowl, combine the plain yogurt, evaporated milk, and sweetened condensed milk. Mix well until smooth.
Stir in the ground nutmeg, ground cinnamon, vanilla extract, and sugar. Adjust the sweetness to taste.
Add the prepared millet couscous to the dairy mixture. Mix well until the couscous is fully coated and incorporated.
If using, stir in the raisins.
Cover the bowl and refrigerate for at least 1-2 hours to allow the flavors to meld and the thiakry to chill.
Enjoy your meal!