Ingredients

• Crust:
• 1 cup graham cracker crumbs
• 2 tablespoons sugar
• 1/4 cup butter, melted
• Filling:
• 1 (8-ounce) package cream cheese, at room temperature
• 1 (14-ounce) can sweetened condensed milk
• 4 egg yolks (from pasteurized eggs)
• 2/3 cup fresh Key lime juice (or regular lime juice if Key limes aren't available)
• 
  Topping (optional)
• 1/3 cup graham cracker crumbs
• 2 teaspoons sugar
• 2 teaspoons finely grated lime zest

Instructions

1. Make the crust: Combine the graham cracker crumbs, sugar, and butter. Spread
2. evenly over the bottom of a lightly buttered 9-inch square pan, packing
3. the crumbs firmly. Refrigerate for at least 1 hour.
4. Make the filling: Beat the cream cheese with the condensed milk and egg
5. yolks until smooth. Beat in the lime juice until smooth. Pour the
6. filling over the chilled crust.
7. Refrigerate for at least 8 hours, or until filling is firm.
8. If desired, make a topping by mixing the graham cracker crumbs, sugar
9. and grated lime zest, and sprinkle lightly over the filling.
10. Refrigerate for at least 8 hours, or until filling is firm. Using a knife dipped in warm water, cut into squares to serve. Keep cold when not serving.