This little 3-ingredient key lime pie is the kind of dessert that shows up at every spring gathering out here in the country and disappears before the coffee is poured. My mother-in-law taught me this recipe when I was a young bride, swearing it was her secret weapon for winning over a crowd: tart, creamy, and just sweet enough, all tucked into a crumbly golden crust. It bakes up in a simple aluminum pie pan, cools in the fridge, and comes out looking like sunshine—pale yellow-green and silky smooth. No fancy gadgets, no long ingredient list, just an old-fashioned, dependable pie that always steals the show at weekend potlucks and family suppers.
Serve this key lime pie well-chilled, straight from the refrigerator so the filling is firm and refreshing. I like to slice it into modest wedges and pass a small pitcher of cold coffee cream or a pot of hot coffee alongside to balance the tartness. It pairs nicely with simple, unfussy foods: grilled chicken, baked ham, or a spring salad with plenty of crisp lettuce. If you want to dress it up for company, scatter a few thin lime slices on the serving plate or sprinkle a light dusting of extra graham crumbs over the top just before bringing it to the table.
3-Ingredient Key Lime PieServings: 8
Ingredients
1 (9-inch) prepared graham cracker pie crust, in an aluminum pie pan
2 (14-ounce) cans sweetened condensed milk
3/4 cup key lime juice (bottled or freshly squeezed), plus a little extra for tasting if needed
Directions
Set your oven to 350°F (175°C) so it can preheat while you mix the filling. Place the aluminum pie pan with the graham cracker crust on a baking sheet to make it easier to move in and out of the oven.
In a medium mixing bowl, pour in the sweetened condensed milk. Slowly whisk in the key lime juice, a little at a time, until the mixture is smooth, thick, and evenly pale yellow-green. The acid in the lime juice will start to thicken the milk almost right away.
Taste a small spoonful of the filling. If you like a sharper tartness, whisk in another tablespoon or two of key lime juice until it suits your taste. Just don’t thin it out too much; it should still be thick and creamy.
Pour the filling into the prepared graham cracker crust, using a rubber spatula to scrape the bowl and smooth the top. Gently tap the pan on the counter once or twice to pop any big air bubbles and level the surface.
Slide the baking sheet with the pie into the preheated oven and bake for 12–15 minutes, just until the edges are set and the very center still has a slight jiggle when you nudge the pan. It should not brown; you are only setting the custard.
Carefully remove the pie from the oven and place it on a cooling rack. Let it cool at room temperature until it is no longer warm to the touch, about 1 hour. The filling will continue to firm up as it cools.
Once the pie has cooled, cover the top loosely with foil or plastic wrap, being careful not to press directly onto the surface, and refrigerate for at least 3–4 hours, or overnight, until thoroughly chilled and fully set.
To serve, slice the pie right in its aluminum pan using a sharp knife wiped clean between cuts. The filling should be smooth and creamy, and the crust crumbly and golden. Return any leftovers to the refrigerator promptly, covered, and enjoy within a few days.
Variations & Tips
If you prefer a slightly sweeter, less tart pie, reduce the key lime juice to 2/3 cup. For a bolder pucker, add up to 1 cup total, a tablespoon at a time, tasting as you go so you don’t overpower the sweetness. You can also use regular lime juice if key limes are hard to find; the flavor will be a touch different but still bright and refreshing. For a firmer, slice-and-serve texture on a hot day, let the pie chill overnight so it cuts cleanly. If your kitchen runs warm, keep the pie in the refrigerator until just before serving to prevent the filling from softening too much. Always use pasteurized sweetened condensed milk and clean utensils, and avoid tasting from the bowl with a spoon you’ve already used in your mouth to keep the filling safe and fresh. Store leftovers covered in the refrigerator and discard if the pie has sat at room temperature for more than 2 hours, especially during summer gatherings. If you’d like a little extra crunch, you can sprinkle a spoonful of crushed graham crackers over the top right before serving without changing the basic 3-ingredient recipe itself.
