Keep the dessert list on the main menu as a primer, but also create a slammer size (usually 4.25"x11") dessert menu with pictures and appetizing, ooey-gooey descriptions.
Roughly 80% of the way through your customer's meal have your servers set that dessert menu on the table, remind the customer to save room dessert, and share an appetizing description of their favorite dessert on the menu.
Maybe even do a promotion for your servers offering an incentive to those who upsell the most desserts.
And... since we are talking about dessert, here is a link to October 2015's featured item:
The Dish >
Dessert Trio of Coconut Panna Cotta, Almond-Shortbread Plum Cobbler with Rosewater Cream and Chocolate Crème Brulée