High recommend Cowhead UHT milk. This is the only milk my child have no issues transitioning to. It is also 100% full cream milk. Not milk solids like some other brands :) https://s.shopee.sg/6pk3WmyONn
I start off by mixing some fresh milk into formula (we gave Cowhead pure milk) then subsequently increase the ratio of fresh milk till fully transit.
find Full Cream UHT milk (powdered or ready to drink). Swap out some formula milk for cows milk and slowly increase the ration