Meats are an important food item for Shrove Tuesday, a carnival day, since meats are given up for Lent. So are fats for the same reason: fats are given up for Lent. As Darren Provine of Rowan University says: "Carnival, which means "farewell to meat." "Carni" as in carnivorous, and "vale" as in valediction, .... One last hamburger before the Lenten fast begins."
Mardi Gras is a day of indulgences before the limitations of Lent, so I would just be sure to have a variety of foods that people recognize as "treats" and not staples. Special cheeses, sweet desserts, special side dishes, and a lot of fun and camaraderie should make for a great party.
This is a great question. I know that you say no pancakes, but you can add M&Ms in the pancakes - just a thought. Also how about foods that people can create for themselves? This creates a greater sense of community. So, how about fajitas? You can get nice steak strips or chicken with a number of roasted vegetables. As for dessert, ice-cream with lots of toppings would be apporpriate. Or if you want, you can make a donut station with a number of dips and toppings for people to do for themselves.
I hosted my first dinner party last December. I think the most important thing to consider is what the people like. Since you seem to have a lot of people, you might also want to consider foods that are easy to serve and keep hot, or foods that don't have to be hot.
This would be an opportunity to impress your guests with a range of different pastries from various parts of the world. You could try kolachi, a sweetbread with a fruity filling, or a Swedish Tea Cake, which is a variation on a cinnamon roll. You might want to google pastries and see what happens.
I would suggest Pazcki (a Polish donut). I would also suggest using up your fats and dairies (based upon the fact that they are forbidden over Lent). If you wish to stay away from pancakes, try crepes instead.
I understand that you are probably ruling out pancakes, but that is the truly traditional dish of Shrove Tuesday. You might want to consider donuts (malasada in Hawaii; spurgos in Lithuania; and paczki in Poland), since that is also a traditional dish. Other forms of pastries are also a traditional fare--especially semlas, a Scandinavian sweet bun filled with almond paste and whipped cream. As far as non-sweets go, split pea and ham soup is a Shrove Tuesday dish in Finland and Estonia, while Icelanders eat English peas. A hot, mulled sweet wine is also traditional in some countries.
Since fats are prohibited, I would suggest ice cream as a dessert. I can't think of a person who doesn't like ice cream. It's easy to serve, easy to buy in varieties, relatively inexpensive, and sure to be popular.
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.