Old Fashioned Key Lime Pie

This is the easy, old-fashioned key lime pie, the kind with no eggs and barely any baking. The magic is chemistry: the acid in the fresh lime and lemon juice reacts with sweetened condensed milk, thickening it into a silky, sliceable filling almost on its own.

Because the acid does the setting, mix the filling gently and don’t overdo it. The recipe is right to warn against over-mixing, which can keep the filling from firming up properly.

A quick five-minute bake just helps it set, and then the fridge does the rest, so chill it at least two hours before slicing.

Fresh lime zest threads tart, fragrant citrus through every bite, and a graham cracker crust gives it that classic buttery base. Finish with a generous swirl of whipped cream to balance the bracing tartness. It’s bright, tangy, and impossibly simple.

Pro Tips

• Mix the filling gently; over-mixing can keep the condensed milk from thickening properly.
• Use fresh lime and lemon juice; the acid is what sets the filling, so bottled won’t do it justice.
• Chill at least two hours before slicing so the pie firms up fully.
• Add the zest for fragrance, but skip the food coloring if you’d rather keep the filling a natural pale shade.

Variations

• Use real key limes for a more authentic, floral tartness.
• Top with toasted meringue instead of whipped cream.
• Add a little extra zest or a splash more lime juice for a sharper, tarter pie.