Macaron is a light, often brightly colored sandwich cookie consisting of two rounded disks made from a batter of egg whites, sugar, and almond flour surrounding a sweet filling (as of ganache, buttercream, or jam). It is a french classic exactly.
Creme brulee is a dessert consisting of a rich custard base topped with a texturally contrasting layer of hardened caramelized sugar. You should definitely try while in Paris.
Onion soup is one of the classic in Paris. This is a rich beef-based broth full of onions cooked until they’re soft and sweet, then covered with cheese and baked in the oven. Especially there is nothing better to warm you up on cold Paris nights.