Crush the graham cracker until very fine. Transfer the crumbs into a large mixing bowl, add sugar, and melted butter. Combine well.
Press crust into 9½ inch pie dish.
Making The Filling
Combinesweetened condensed milk, egg yolks, and fresh lime juice in a large mixing bowl. Use an electric mixer and beat on medium-high speed until the mixture is smooth and creamy.
Pour filling over the graham cracker crust and bake at 350° Fahrenheit for 15 minutes.
Making The Sweet Cream Topping
Beat cold heavy whipping cream for several minutes on medium-high speed until soft peaks form. Add powdered sugar and beat until well combined.
Spread the sweet cream topping over the cool-to-the-touch key lime filling. Chill for 2 hours.