Preheat oven to 350 degrees.
Using a food processor, grind graham crackers into crumbs.
Place crumbs in a bowl and add butter and sugar. Mix well.
Put foil cupcake liners into the cupcake pan.
Divide crumbs evenly between foil cups. About 1 Tablespoon each. Press firmly into the bottom.
In a separate bowl throughly combine eggs, sweetened condensed milk, lime juice, zest, and greek yogurt.
Fill the baking cups about 1/4" from the top of the liner and bake for 12-15 minutes.
Cool completely. Garnish with whipped cream