Step 1

Combine melted butter and sugar in a medium bowl. Stir in crushed graham crackers.

Step 2

Spread evenly into 9-inch pie plate and press onto bottom and sides to form an even crust. The bottom of a measuring cup works great for pressing the crumbs firmly into the pie plate.Chill for an hour until firm OR bake at 375-degrees for 5 min and allow to cool before filling.

Step 3

Preheat oven to 350-degrees. Zest key limes until there are 2 teaspoons of zest, then juice them. Pour the fresh key lime juice into a 1/2 cup measuring cup.If the 1/2 cup isn't filled, add bottled key lime juice to fill it completely.

Step 4

Beat the egg yolks until they are thick and turn to a light yellow. Use a stand mixer or an electric mixer. Slowly add sweetened condensed milk while mixing on a low speed.

Step 5

Gradually add the key lime juice and zest and continue to mix on a low speed just until blended.

Step 6

Pour the mixture into the prepared pie shell and bake 15 minutes. Remove and let cool.

Step 7

Serve with a garnish of whipped topping and a small slice of lime if desired. Store pie in refrigerator until ready to serve