The traditional reason for Shrove Tuesday (or Mardi Gras) was to use up food items that were prohibited during Lent, the weeks of fasting and penitence prior to Easter. If you wish to observe this practice, you could choose items for your menu accordingly. Meats of all types, eggs, and dairy products were forbidden during Lent in much of Europe during the Middle Ages.
Combining the restrictions on eggs and milk with the prohibition of fats such as butter led to the wide adoption of pancakes as a traditional Shrove Tuesday dish. However, other types of pastries could be included on your menu in place of or in addition to pancakes.
You might consider offering more than one type of meat, since Shrove Tuesday would have been a final opportunity to have meat before Lent in many places.