اللّهُـمَّ بارِكْ لَنا فيهِ وَزِدْنا مِنْه
Allahumma barik lana feehi wazidna minh
Translation
O Allah, bless it for us and give us more of it.
When to recite
Recited when drinking milk. The Prophet said there is nothing that suffices as both food and drink except milk.
Source / Reference
Abu Dawud 3/347, At-Tirmithi 4/288