"Whomever Allaah feeds, should say:

اللَّهُمَّ بَارِكْ لَنَا فِيهِ وَأَطْعِمْنَا خَيْراً مِنْهُ

O Allah, bless us in it and provide us with better than it.

Allaahumma baarik lanaafeehi wa 'at'imnaa khayranminhu.

...and whomever Allaah gives milk to drink, should say:

اللَّهُمَّ بَارِكْ لَنَا فِيهِ وَزِدْنَا مِنْهُ

O Allah, bless us in it and give us more of it.

Allaahumma baarik lanaa feehi wa zidnaa minhu.

At-Tirmithi 5/506. See also Al-Albani, Sahih At-Tirmithi 3/158.