Preheat your oven to 350 F, and lightly grease a pie plate with non-stick cooking spray.
In a food processor, crush about 1 1/2 packages of graham crackers.
Melt the butter and mix with 1 1/4 cups graham cracker crumbs and 3 Tablespoons granulated sugar.
Press the graham cracker mixture into the bottom and sides of your pie plate and bake in the preheated oven for 10 minutes.
Beat the cream cheese in a large mixing bowl and mix in the sweetened condensed milk.
Zest and juice the key limes (regular limes work too) and mix into the cream cheese mixture.
Pour the cream cheese mixture into the pre-baked graham cracker pie crust and *let set in the refrigerator for about 8 hours.
Top with whipped cream, lime zest and a few lime slices.
Enjoy a refreshing Key Lime Pie for dessert!