Preheat your oven to 350°F (175°C). Line a 9x9-inch baking pan with parchment paper.

In a food processor, pulse about 1 ½ cups of graham crackers until finely crushed. Add ½ cup of melted butter and mix until the texture resembles wet sand. Press this mixture firmly into the bottom of the prepared pan.

Bake for 10 minutes or until golden and fragrant, then let it cool slightly.

In a mixing bowl, combine the key lime juice, zest, one can of sweetened condensed milk, 1 teaspoon of vanilla extract, and ½ cup of sour cream. Whisk until smooth and creamy.

Gently stir in 4 egg yolks into your creamy filling.

Carefully pour the filling over the crust and spread it evenly. Bake for 15-20 minutes until set but slightly jiggly in the center.

Allow the Lime Pie Bars to cool at room temperature for about 30 minutes. Transfer to the refrigerator and chill for at least 2 hours.

In a separate bowl, whip 1 cup of heavy cream until stiff peaks form.

Spread the whipped cream evenly over the chilled bars. Slice into squares or rectangles with a sharp knife.