Eating desserts after having the meal has 2 main advantages:
1. The blood sugar spike is minimized since in your meal, your consuming complex carbohydrates which only gradually increase blood sugar levels. After that the consumption of the sweet relatively does not cause such a big spike.
2. Eating desserts on an empty stomach/when fully hungry causes a much greater craving for those items. Eating them on a full stomach comparatively causes much lower craving.
Another way suggested to reduce sugar craving is to frequently keep consuming small amounts of food.