Chinese peanut dessert (fah sung thong)

Into a blender, add the peanuts,milk and water. Spin either to a smooth paste or a coarse one (depend on which you prefer). I wanted some mild crunchy taste, therefore it was a coarse paste.
Add the paste in a pan and pour in the water.
Let it simmer over very low heat.
Add more water if you prefer it to be more diluted.
Put in the butter and stir to melt.
Just another two or three mins, remove from heat.
Before serving, top up with the whole peanuts kept aside and sprinkle the sesame seeds.