I like to bring dinner party desserts that be taken off a plate by hand, rather than cut and served (unless I'm hosting). My faves are:
Cook's Illustrated chocolate cream cheese brownies (yes they are brownies but beautiful and holy cow delicious):
https://blog.bimajority.org/2014/09/01/other-peoples-recipes-cooks-illustrateds-cream-cheese-brownies/
Melissa Clark's cultured butter cookies:
https://cooking.nytimes.com/recipes/1015209-cultured-butter-cookies
NYTs Rich Chocolate Cookies (cut into holiday shapes like large snowflakes):
https://cooking.nytimes.com/recipes/1013392-rich-chocolate-cookies