Mix your 1.5 cups graham cracker crumbs with 0.5 cup melted butter and 2 tablespoons sugar in a bowl. Stir until the mixture looks like wet sand—you want everything evenly coated. Press firmly into a 9-inch pie dish, getting it up the sides too.

Pop that crust into the freezer for 15 minutes while you make the filling. This helps it set and prevents a soggy bottom, which trust me, nobody wants. The texture stays crispy and holds up beautifully under the creamy lime layer.

Grab a large bowl and whisk together 1 (14 oz) can sweetened condensed milk with 0.75 cup fresh key lime juice. Mix until smooth and combined—don't worry if it looks thick at first. This is gonna be so good, I promise.

In a separate bowl, combine your heavy whipping cream, 2 tablespoons powdered sugar, 1 teaspoon lime zest, 0.5 teaspoon salt, and 0.25 teaspoon cream of tartar. Whip on medium-high speed until you get stiff peaks, which takes about 3-4 minutes. Don't overmix or you'll accidentally make butter (yes, I learned this the hard way).

Gently fold that whipped cream into the lime mixture using a spatula. Use a few big strokes instead of lots of little ones—you want to keep all that fluffy air inside. The filling should look light, airy, and gorgeously pale green.

Pour everything into your chilled crust and spread evenly with a spatula. Top with 0.75 cup toasted coconut flakes, then drizzle 1 tablespoon lime juice over everything for extra brightness. The no bake key lime pie is basically done at this point.

Cover loosely with plastic wrap and refrigerate for at least 4 hours, ideally overnight. The filling sets up beautifully and flavors meld together perfectly after sitting. Slice with a hot, wet knife for clean cuts.