In a medium-sized bowl, whisk together the melted butter and sugar. Fold in the graham cracker crumbs.

Transfer this mix to a 9-inch pie dish, pressing down on both the base and sides to create an even crust. Tip: A flat base of a measuring cup can be effective in pressing the crumbs firmly.

Let it chill for about an hour till it's firm. Alternatively, bake it at 375°F for 5 minutes. Let it cool before adding the filling.

Start by preheating your oven to 350°F.

Zest the key limes until you gather about 2 teaspoons. Post that, juice them. Collect this fresh juice into a 1/2 cup. If it doesn't fill up, you can use the Nellie & Joe's Key West Lime Juice to top it up.

In a separate bowl, whisk the egg yolks until they're thick and have a pale yellow hue. Ideally, use a stand mixer or an electric hand mixer. While still mixing, pour in the sweetened condensed milk steadily.

As you keep mixing, slowly introduce the key lime juice and zest until just blended.

Now, pour this concoction over your prepared crust and bake for 15 minutes. Post baking, let it cool.

Serve chilled. Garnish with whipped topping or a tiny lime wedge for an added flair. Always refrigerate until you're ready to dig in!