Eruv Tavshilin

"One is not permitted to prepare foods on Yom Tov for Shabbat (or for any other day). Therefore, if the holiday falls on Friday, one may not prepare for the Shabbat unless an Eruv Tavshilin has been made.It is the function of the Eruv Tavshilin to indicate that the preparation for Shabbat actually began before Yom Tov commenced. Food is set aside before the holiday begins and then eaten on Shabbat (preferably for Seudah Shlishit). The ritual of Eruv Tavshilin is performed on Erev Yom Tov, before Yom Tov begins. Take a matzah (or any baked food) with a cooked food (such as an egg, a piece of chicken, or fish) and set it aside to be eaten on Shabbat. While setting it aside, recite the Bracha:
"Baruch Atah Adonai, Eloheinu Melach HaOlam, Asher Kidishanu B`Mitzvotov, Vitzivanu, Al Mitzvat Eruv. "
One also recites an Aramaic declaration.
"Bahadayn aruva yehay sharay lanah la'aphoray ulevashoolay uleatemoonay oleadelookay sheragah ulesakana uleme'ebad tzarecanah, miomah tavah leshabesah" which translates as: "With this Eruv, it will be permitted for us to bake, cook, broil, preserve warmth, light candles, and do all necessary things on Yom Tov for Shabbat." The Declaration is also found in the Siddur."
http://www.ortorah.org/erv_tav.htm

Note, that since Jews in the diaspora celebrate Shavuot on Shabbat, in addition to Friday, the Torah reading on Saturday will be related to Shavuot. However, in Eretz Yisrael, the Torah reading will be the parsha of the week. Rabbi Lazer Brody notes that for six weeks, those outside of Eretz Yisrael will be one week behind the Parsha that is read in Israel.