For most Ashkenaz, ethnic European Jews, especially outside of Israel this question probably sounds sacrilegious. When I was
learning Torah Judaism, becoming religious I was told that eating cheesecake was as intrinsic to celebrating Shavuot as matzah was on Passover.
The culinary highlight of my in-laws staying with us for Shavuot was the homemade blintzes my mother-in-law made. I had no idea that there was a way to make them outside of purchasing the frozen variety from the supermarket. That was the only type ever found in my parents' home.
Over the years I learned to make various dairy kugels and an easy version of Eggplant Parmesan, which would have most cooks outraged by its simplicity and lack of authenticity. But that was the only way I would do it. In principle I do not cook recipes that involve three or even two steps besides noodle kugels. And I was overjoyed to discover from a friend that you actually don't need to precook lasagna pasta; just layer the dry noodles as if they had been cooked and add extra water. Here in Israel, we have a great variety of kosher cheeses, so if you have the right breads and crackers you barely have to cook.
Then my daughter married a Tunisian Jew, and our traditional Shavuot menu was suddenly under attack. His family, like many North African Jews, do not each much dairy and certainly do not consider cheese to be suitable for Jewish Holidays. They barbecue on Jewish Holidays for the "morning" meal. He considered our "just like Shabbat" menu to be an affront on Jewish food. They barbecue on Rosh Hashannah, Succot, Simchat Torah, Passover and yes, even eat grilled meat on Shavuot! Cheesecake, blintzes, lasagna, pizza and all those cheesy dishes aren't part of their traditional Shavuot menu.
Our compromise for their coming to us for Shavuot was to have one dairy meal and one meat meal. Recent years they've established the custom to be with his family, so the younger generation can learn with their cousins.
Back at the ranch, as the saying goes, we've been eating less and less cheese in our home. It's expensive and not very suitable for me and my husband's diet regime. I've also eliminated blintzes, since I never learned how to make the homemade ones and they aren't on my approved food list. To celebrate Shavuot, I get nice fish to cook and we do splurge on some good cheeses. Our favorite fish is salmon, which even on sale is more expensive than the beef I buy. And of course I make lots of vegetables and salads.
So, what do you serve on Shavuot?