Preheat oven to 325°F. Coat a 9-inch springform pan with cooking spray. Put a kettle of water on to boil for the water bath. Wrap the outside of the pan with a double thickness of foil.

To prepare crust: Grind vanilla snaps in a food processor. Add oil and process until the crumbs are moistened. Press crumbs evenly into the bottom of the prepared pan.

To prepare filling: Puree cottage cheese in a food processor (use a clean workbowl) until smooth, scraping down the sides once or twice. Add cream cheese, granulated sugar (or Splenda), brown sugar and cornstarch. Process until very smooth. Add egg, egg whites, yogurt, orange zest, orange juice and vanilla; process until smooth. Pour over the crust.

Place the cheesecake in a shallow roasting pan and pour in enough boiling water to come 1/2 inch up the outside of the springform pan. Bake until the edges are set but the center still jiggles when the pan is tapped, 50 to 60 minutes.

Turn off the oven. Spray a knife with cooking spray and run it around the inside edge of the pan. Let the cheesecake stand in the oven, with the door ajar, for 1 hour. Remove the cheesecake from the water bath and remove the foil. Refrigerate, uncovered, until chilled, about 2 hours.

To glaze & garnish cheesecake: Shortly before serving, combine marmalade and orange liqueur (or juice) in a small saucepan. Heat over low heat, stirring, until melted and smooth. Place cheesecake on a serving platter and remove pan sides. Brush glaze over the top of the cheesecake. Make a slit in each orange slice, then twist and wrap it into a rosette. Garnish cheesecake with the orange rosettes and mint.