Line a colander or sieve with a double layer of cheesecloth that has been rinsed out and squeezed dry; allow cheesecloth to extend over edge of colander.
Spoon yogurt into colander, and fold edges of cheesecloth over to cover yogurt.
Place colander in a large bowl; refrigerate 12 hours.
Scrape yogurt into a bowl, using a rubber spatula; discard liquid.
Coat a 10-inch springform pan with cooking spray.
Sprinkle crushed gingersnaps evenly over bottom of springform pan.
Position knife blade in food processor bowl.
Add Neufchatel cheese and sugar; process until light and fluffy.
Add drained yogurt, and process until smooth.
Add eggs, egg whites, orange juice concentrate, orange rind, and orange extract; process until mixture is well blended.
Spoon mixture over crushed gingersnaps.
Bake at 350° for 35 minutes (center will be soft but will firm when chilled).
Remove from oven, and let cool to room temperature on a wire rack.
Cover and chill 4 hours or until set.
Spread marmalade evenly over top of cheesecake.
Garnish with orange rind curls, if desired.
Cover and chill 1 hour or until marmalade is set.