Preheat your oven to 350°F. In a mixing bowl, combine ground graham crackers, toasted pecans, melted butter, and powdered sugar until the mixture resembles wet sand. Press into an 8 or 9-inch springform pan. Bake for 10 minutes until set and lightly golden, then let it cool slightly.

Zest and juice your key limes to yield about 1 cup of juice. In a large bowl, whisk together the lime zest, lime juice, sweetened condensed milk, egg yolks, sour cream, vanilla extract, and sea salt until smooth. Pour into your cooled crust.

Pour the filling into the pre-baked crust and smooth the top with a spatula. Bake for 20 to 25 minutes, until the center jiggles slightly but is mostly set. Cool at room temperature for about 30 minutes.

Transfer the pie to the refrigerator for at least 4 hours, or overnight. This chilling time is crucial for achieving the creamy texture.

On the day of serving, whip heavy cream in a food processor until thick. Spread over the chilled pie and optionally garnish with additional lime zest or meringue.