Key Lime Pie: Preheat the oven to 350 degrees F (177 degrees C) and place the oven rack in the center of the oven. Butter or lightly spray with a non stick vegetable spray, a 9 inch (23 cm) pie or tart pan.

Graham Cracker Crust: Mix together the graham cracker crumbs, sugar, and melted butter. Press onto the bottom and up the sides of the prepared pan. Bake for about 10 minutes or until set and lightly browned. Remove from oven and place on wire rack to cool while you make the filling

Filling: In the bowl of your electric mixer, with the whisk attachment, beat the egg yolks until pale and fluffy (2-3 minutes). Gradually add the condensed milk and beat until light and fluffy (3-5 minutes). Scrape down the sides of the bowl and then beat in the lime juice and zest. 

Pour the filling over the crust and bake for about 10 - 15 minutes, or until the filling is set. Remove from oven and place on a wire rack to cool. Once it has completely cooled, cover and refrigerate for several hours or overnight.

Once the filling has chilled, in the bowl of your electric mixer, with the whisk attachment (or with a hand mixer), beat the whipping cream and sugar until stiff peaks form. Either pipe (I used a Wilton 1M star tip) or place mounds of whipping cream on top of the filling. Can be stored in the refrigerator for a few days.

Makes 1 - 9 inch (23 cm) pie or tart.