Can one spread kosher cream cheese with a treif knife? I'm looking for sources (obviously will AYCLOP for final psak) Thank you,
If the knife is cold and clean, and the cream cheese doesn't contain onions/hot peppers, then this is permitted.
R Yitzchok Yaakov Fuchs (in his book Hakashrut, p. 668) writes
A completely clean knife that is found in a non-kosher kitchen may be used to cut cold fruit and vegetables however it may not be used to cut sharp foods.
R Binyamin Tabady and R Yonathan Jessurun both told me they permitted this on a one-off basis, i.e., not something to be done regularly.