Key Lime Meringue Pie

This is the Floridian classic key lime pie crowned with billowy toasted meringue instead of the usual whipped cream. The meringue gives the pie a dramatic profile and an extra textural element, with crisp golden peaks against the smooth tart filling.

Real key lime juice is essential. Persian (regular) limes work in a pinch but lack the floral, slightly more bitter complexity that defines authentic key lime pie. Bottled key lime juice is acceptable when fresh isn’t available and gives more consistent results than fresh juicing tiny key limes.

The sweetened condensed milk does triple duty: it sweetens, thickens and creates the texture. The acid in the lime juice causes the proteins in the milk to set up into a silky custard without any added gelatin or eggs cooked over heat. This chemistry is why key lime pie can be made without baking the filling.

Cream of tartar in the meringue is the secret to stable peaks. It stabilizes the egg whites and prevents weeping (the watery layer that forms between filling and meringue in unstable pies). Skip it and the meringue collapses overnight.

Add the sugar 1 tablespoon at a time once the whites have started to whip. This gradual addition is what produces stiff peaks with that glossy sheen. Dumping sugar in all at once gives soft droopy meringue.

Seal the meringue all the way to the pastry edge. This prevents the meringue from shrinking inward as it cooks, which would leave a gap where weeping liquid pools.

Pro Tips

• Use egg whites at room temperature for the highest meringue volume. Cold whites refuse to whip properly.
• Ensure no yolk gets into the whites. Even a speck of fat prevents whipping.
• Bake just long enough to brown the meringue peaks. Overbaking dries it out and crackles the surface.
• Cool completely on the counter before refrigerating to prevent condensation on the meringue.

Variations

• Top with toasted coconut flakes for a tropical twist.
• Add 1 teaspoon of grated lime zest to the filling for a more intensely citrus version.
• Skip the meringue and top with fresh whipped cream and a sprinkle of lime zest for a simpler presentation.