I think I just found my favorite dessert, Shibuya Honey Toast @ After You.
The "toast" is reminiscent of the original RotiBoy, without the coffee flavor. Add a couple scoops of ice cream, banana, whipped cream and nuts, and we're almost done. It's is finished off with a drizzle of maple syrup!
The beast will set you back about 200 baht, but it will feed 2~3 people.
Although we visited the La Villa branch, there are "After You locations all over Bangkok. Be forewarned; these places are quite busy.