Heat oven to 350 degrees F. Butter a 9-inch pie pan, cast iron pan or springform pan.
Add graham crackers and sugar into the bowl of a food processor. Pulse until small crumbs form. Add melted butter and combine.
Press crumb mixture into pan, forming a neat border around the edge and slightly up the sides.
Bake until set and golden, about 8 minutes, and set aside. Keep oven on.
In an electric mixer with a wire whisk attachment, beat the egg yolks and lime zest at high speed until very fluffy, about 5 minutes.
Gradually add the condensed milk and continue to beat until thick, 3 or 4 minutes longer.
Lower the mixer speed and slowly add the lime juice, mixing until just combined.
Pour mixture into the crust.
Bake for 10 minutes or until filling has just set. Cool for 20 minutes on a wire rack.
Mix together sour cream and confectioners' sugar until well combined. Spread thin layer over Pie. Refrigerate, until ready to serve.
Prepare my Homemade Perfect Whipped Cream before serving. Using a Food Processor or Electric Hand Mixer, whip heavy cream and sugar together until stiff peaks form. Pipe on top of pie and garnish with Lime Zest Garnish.
For Pressure Cooker
Use a 7 inch Pan. Add 1.5 cups of water to pressure cooker cooking pot and place a Trivet in pot. Using a Foil Sling, lower Pan into Pressure Cooker.Lock on lid and close Pressure Valve. Cook at High Pressure for 10 minutes.When Beep sounds, wait 10 minutes and then release all pressure. Cool on a wire rack.
Freeze for 10 minutes prior to serving. Key Lime Pie is best when very cold.