Preheat oven to 300 degrees F. Line 12 muffin tins with foil liners. Lightly spray with oil. Set aside.
In a small food processor or blender (I used my NutriBullet) process graham crackers into crumbs, then pulse together with butter until combined.
Evenly divide graham cracker mixture between the 12 liners, pressing with back of a tablespoon to flatten.
Bake graham cracker crust for 8-10 minutes. Set aside to cool for 10 minutes while you make the filling.
In a medium mixing bowl using an electric mixer, beat together softened cream cheese until light and fluffy. Add in yogurt and sugar, beating again until smooth. Then add in egg, egg white, juice of limes and zest. Beat until just combined.
Evenly distribute cheesecake batter into liners with baked graham cracker crusts. Bake for 12-15 minutes, until the middle is set.
Remove from oven and allow the pan to cool to room temperature, then place in the fridge to chill for 2 hours before serving.
Prep time includes chilling the cheesecakes -These Key Lime Cheesecakes could be made a day in advance as well, chilling the cheesecake cups overnight.