Cooking early during the day on a Friday Yom Tov for Shabbat

Hi,

This one is complicated, but it's a worthwhile point:

The core leniency in the Eruv Tavshilin is this:

The prohibition against cooking on a Friday Yom Tov for the ensuing Shabbat is rabbinic, since on a biblical level one could argue that guests might still arrive on Yom Tov and eat the food that day.

Therefore, the rabbis were able to create an "Eruv Tavshilin" enactment circumventing their own rabbinic prohibition, permitting cooking on Yom Tov for Shabbat.

Based on this logic, one should only exploit Eruv Tavshilin to cook early in the day on Yom Tov for Shabbat, at a time when guests might realistically arrive.

(Mishneh Berurah 527:3)

Have a great day,
Mordechai