הגהות הרמ״א
...ונוהגין בכל מקום לאכול מאכלי חלב ביום ראשון של שבועות ונראה לי הטעם שהוא כמו השני תבשילין שלוקחין בליל פסח זכר לפסח וזכר לחגיגה כן אוכלים מאכל חלב ואח"כ מאכל בשר וצריכין להביא עמהם ב' לחם על השלחן שהוא במקום המזבח ויש בזה זכרון לשני הלחם שהיו מקריבין ביום הבכורים:
Gloss of Rabbi Moshe Isserles
...We have a custom everywhere to eat dairy food on the first day of Shavuot. And it seems to me that the reason is: It is like the two foods that are taken on the evening of Passover, as a reminder of the Passover sacrifice and a reminder of the Sacrifice of Rejoicing, so too we eat a dairy food followed by a meat food, and we bring with them two loaves on the table in place of the altar, and thus there will be a reminder of the two loaves that were brought on "the day of the bringing of the first fruits (bikkurim)."
This is a technical answer, and follows from the laws of kashrut. But this is a very convoluted way to ensure that one eats dairy! And what's up with the two loaves of bread? Tip: Try searching Sefaria for "two loaves of bread."
(יז) מִמּוֹשְׁבֹ֨תֵיכֶ֜ם תָּבִ֣יאּוּ ׀ לֶ֣חֶם תְּנוּפָ֗ה שְׁ֚תַּיִם שְׁנֵ֣י עֶשְׂרֹנִ֔ים סֹ֣לֶת תִּהְיֶ֔ינָה חָמֵ֖ץ תֵּאָפֶ֑ינָה בִּכּוּרִ֖ים לַֽיהוָֽה׃
(17) You shall bring from your settlements two loaves of bread as an elevation offering; each shall be made of two-tenths of a measure of choice flour, baked after leavening, as first fruits to the LORD.
Now I understand where the bread comes from...but where's the cheesecake? And what is the connection to Passover? Tip: Try searching Sefaria for "cheesecake."
Based on what I found, I'm intrigued by the connections to milk, and especially to milk and honey.
(י) גם נהגו לאכול דבש וחלב בחג שבועו׳ מפני התור׳ שנמשלה לדבש וחלב כמו שכתוב דבש וחלב תחת לשונך.
It is customary to eat honey and milk on the holiday of Shavuot, because of the Torah, which is compared to milk and honey, as it says, "honey and milk are under your tongue."
Where does it say that "honey and milk are under your tongue?" What is the Kol Bo quoting?? Tip: Try searching for this quote on Sefaria!
נֹ֛פֶת תִּטֹּ֥פְנָה שִׂפְתוֹתַ֖יִךְ כַּלָּ֑ה דְּבַ֤שׁ וְחָלָב֙ תַּ֣חַת לְשׁוֹנֵ֔ךְ וְרֵ֥יחַ שַׂלְמֹתַ֖יִךְ כְּרֵ֥יחַ לְבָנֽוֹן׃
Sweetness drops From your lips, O bride; Honey and milk Are under your tongue; And the scent of your robes Is like the scent of Lebanon.
Oh there it is! Click on the title (Song of Songs) to see this verse in context.
What does this have to do with Shavuot?
רַבָּנָן אָמְרֵי כָּל מִי שֶׁאוֹמֵר דִּבְרֵי תוֹרָה בָּרַבִּים וְאֵינָן עֲרֵבִין עַל שׁוֹמְעֵיהֶן כִּדְבַשׁ וְחָלָב הַמְעֹרָבִין זֶה בָּזֶה, נוֹחַ לוֹ שֶׁלֹא אֲמָרָן. רַבִּי יוֹחָנָן וְרֵישׁ לָקִישׁ, רַבִּי יוֹחָנָן אָמַר כָּל מִי שֶׁאָמַר דִּבְרֵי תוֹרָה בָּרַבִּים וְאֵינָן עֲרֵבִין לְשׁוֹמְעֵיהֶן כְּכַלָּה זוֹ שֶׁעֲרֵבָה עַל בְּנֵי אָדָם בְּחֻפָּתָהּ, נוֹחַ לוֹ שֶׁלֹא אֲמָרָן. רֵישׁ לָקִישׁ אָמַר כָּל מִי שֶׁאָמַר דִּבְרֵי תוֹרָה וְאֵינָן עֲרֵבִין עַל שׁוֹמְעֵיהֶן כְּכַלָּה זוֹ שֶׁעֲרֵבָה עַל בַּעֲלָהּ בִּשְׁעַת חֻפָּתָהּ, נוֹחַ לוֹ שֶׁלֹא אֲמָרָן.
The Rabbis say: Anyone who says words of Torah in public, and they are not pleasant to those who hear them like honey and milk mixed together, it would have been better if they had not been said. Rabbi Yochanan and Reish Lakish: Rabbi Yochanan said: Anyone who says words of Torah in public, and they are not pleasant to those who hear them like a bride who is pleasing to all at her chuppah, it would have been better if they had not been said. Reish Lakish said: Anyone who says words of Torah in public, and they are not pleasant to those who hear them like a bride who is pleasing to her husband at her chuppah, it would have been better if they had not been said.
Torah (at its best) is like a bride...and also like honey and milk: sweet and delicious and comforting. And so, things that are sweet and delicious and comforting can remind us of Torah (at a time when we, the Jewish people, are also compared to a bride!)
Rituals of Childhood: Jewish Acculturation in Medieval Europe
by Ivan G. Marcus
pg. 1
On Shavuot, we are all children, approaching the study of Torah as if for the first time. We reenact the revelation by opening our mouths to receive the deliciousness of Torah...and cheesecake!