Butter 9" pie dish or spring form pan. Crust crackers into fine crumbs. Melt remaining butter and mix thoroughly with crumbs. Press mixture evenly on bottom and up sides of dish or pan. Peel 5 ortaniques, removing all peels and with albedo (pith) and extract wedges and arrange them evenly two layers on crust. Squeeze the juice from the 6th ortanique into a mixing bowl. Add vanilla extract and eggs. Beat in sugar and then cheese until the mixture is smooth. Pour over the ortaniques and bake for 35 minutes in a preheated oven at 325° or until firm. Increase heat to high and brown top of cake for a few seconds. Cool, then refrigerate overnight.