Preheat your oven to 350°F (175°C). Lightly grease a 9-inch glass or ceramic pie dish.

Place the saltine crackers in a large zip-top bag and crush them with a rolling pin until you have fine crumbs with a few small pieces for texture. Alternatively, pulse them in a food processor, being careful not to turn them into powder.

In a mixing bowl, combine the crushed saltine crackers, granulated sugar, and fine sea salt. Stir to blend, then pour in the melted butter and mix until the crumbs look like damp sand and hold together when pressed in your hand.

Pour the crumb mixture into the prepared pie dish. Press the crumbs firmly and evenly across the bottom and up the sides using the bottom of a measuring cup or glass, making sure the center is not too thin. Bake for 10–12 minutes, until lightly golden and fragrant. Remove from the oven and let cool for about 10 minutes while you prepare the filling.

In a medium bowl, whisk the egg yolks until smooth and slightly thickened. Add the sweetened condensed milk and whisk until the mixture is silky and pale.

Stir in the lemon juice, lime juice, lemon zest, and lime zest until fully combined. The mixture will thicken slightly as the citrus reacts with the condensed milk.

Pour the creamy citrus filling into the slightly cooled saltine crust. Return the pie to the oven and bake at 350°F (175°C) for 15–18 minutes, until the edges are set and the center has a gentle jiggle when the pan is shaken.

Remove the pie from the oven and cool on a rack until it reaches room temperature. Once cooled, cover loosely with plastic wrap and refrigerate for at least 4 hours, or overnight, until fully chilled and set.

When ready to serve, beat the cold heavy whipping cream with powdered sugar and vanilla extract until soft-to-medium peaks form.

Spread or pipe the whipped cream over the chilled pie. Garnish with extra citrus zest or thin lemon/lime slices and a tiny pinch of flaky sea salt, if using. Slice with a sharp knife, wiping the blade between cuts, and serve cold.