From my research, it seems as though it is appropriate to to a dessert reception between 1pm – 4pm and after an 7:30pm. Just be sure to add “Dessert Reception following Ceremony” to the bottom of your invitation. A good menu would include, bride’s cake, groom’s cake, assorted cookies, fruit, and maybe some type of bar or square (ie. Cream cheese bar, lemon square).
Just because you are having a dessert reception doesn’t mean that it can’t be formal. You can have your guests dress up if you would like. Another great idea would be to hire a musician such as a harpist or saxaphonist to add a classical or jazzy feel. You can still slow dance and have as much fun as would at any reception. Be creative as you want to be and happy planning.