Prep the oven and pan: Preheat your oven to 350°F (175°C). Lightly butter a 9-inch pie dish.

Make the crust: In a bowl, combine graham cracker crumbs, sugar, and melted butter. Stir until the crumbs are evenly moistened and clump slightly when pressed.

Press and bake the crust: Firmly press the mixture into the bottom and up the sides of the pie dish. Bake for 8–10 minutes until lightly golden. Let it cool slightly while you make the filling.

Whisk the filling: In a mixing bowl, whisk egg yolks until slightly thickened, about 1 minute. Add sweetened condensed milk, lime juice, lime zest, vanilla (if using), and a pinch of salt. Whisk until smooth and creamy.

Fill the crust: Pour the filling into the warm crust. Tap the pie dish gently on the counter to remove air bubbles.

Bake: Bake at 350°F (175°C) for 12–15 minutes. The edges should be set, and the center should still have a soft jiggle—not wet or soupy.

Cool and chill: Let the pie cool to room temperature, then cover and refrigerate for at least 3 hours, preferably 4–6, until fully set.

Whip the cream: Beat heavy cream with powdered sugar until soft-to-medium peaks form. Don’t overbeat. Spread or pipe over the chilled pie.

Garnish and serve: Add a sprinkle of lime zest or a few thin lime slices. Slice with a warm, clean knife for neat portions. Enjoy cold.