It might depend on how the pastry was made, since you can’t mix dairy and meat if the pasty had involved use of any animal fats that might mean it was non-kosher.
Without knowing all the details of the movie, this note above would be the likely correct answer. The prohibition against mixing meat and milk products (such as cream, etc.) is derived from a few verses in the Torah, namely Exodus 23:19 and 34:26:
“The choicest first-fruits of thy land thou shalt bring into the house of the LORD thy God. Thou shalt not seethe a kid in its mother’s milk.”
and Deut. 14:21:
“Ye shall not eat of any thing that dieth of itself; thou mayest give it unto the stranger that is within thy gates, that he may eat it; or thou mayest sell it unto a foreigner; for thou art a holy people unto the LORD thy God. Thou shalt not seethe a kid in its mother’s milk.”
The traditional interpretation of boiling a kid in its mother’s milk is derived to mean that one should not eat milk and meat at the same meal. The strict time frame between non-consumption of meat and milk is considered to be 6 hours, which comes from a teaching by Maimonides.
Nazis would not have followed these dietary restrictions, much less know their intricate details. By contrast, an Orthodox Jew would follow these dietary regulations.