1. Preheat oven to 350°F (175°C). Line 9×9-inch baking pan with parchment paper, leaving overhang for easy removal.
2. In bowl, mix graham cracker crumbs, melted butter, and sugar until mixture resembles wet sand and holds together when squeezed.
3. Press mixture evenly into bottom of prepared pan using measuring cup bottom for even compaction.
4. Bake crust for 10 minutes until set and lightly golden. Remove and let cool slightly while preparing filling.
5. In another bowl, whisk together egg yolks, sweetened condensed milk, Key lime juice, and zest until completely smooth.
6. Pour lime mixture over warm crust, spreading evenly to edges.
7. Bake additional 15 minutes until center is just set but still slightly jiggly—it will continue setting as it cools.
8. Cool completely to room temperature, then refrigerate at least 2 hours until fully set.
9. Using parchment overhang, lift from pan and cut into 16 squares with sharp knife, wiping clean between cuts.
10. Top each square with whipped cream and garnish with lime slice before serving chilled.

Nutrition Information (Per Serving):

• Calories: 245
• Carbohydrates: 32g
• Protein: 4g
• Fat: 12g
• Fiber: 1g
• Sodium: 85mg
• Vitamin C: 15% DV (from Key lime juice)
• Calcium: 12% DV (from condensed milk)

Rich in vitamin C from citrus and calcium from dairy, though definitely an indulgent treat.

Notes:

• Pre-bake crust for crispy texture—don’t skip this step
• Room temperature eggs mix more easily and create smoother filling
• Don’t overbake filling—center should still jiggle slightly when done
• Chill thoroughly for clean cuts and proper texture
• Fresh Key lime zest adds aromatic oils that enhance flavor significantly

Storage Tips:

• Improve overnight as flavors meld together beautifully
• Store covered in refrigerator up to 3 days
• Add whipped cream and garnish just before serving
• Can be frozen up to 1 month wrapped well

Serving Suggestions:

• Summer party: Perfect make-ahead dessert for outdoor entertaining
• Tropical theme: Serve with coconut shavings and tropical flowers
• Elegant finish: Individual plating with artistic whipped cream swirls
• Casual gathering: Cut into larger squares for satisfying portions

Mix It Up (Recipe Variations):

• Coconut Lime: Add toasted coconut to crust for tropical twist
• White Chocolate: Drizzle melted white chocolate over finished bars
• Mini Versions: Make in muffin tins for individual servings
• Passion Fruit: Swirl passion fruit pulp into filling for complexity

What Makes This Recipe Special:

These bars honor the Florida Keys dessert tradition that began in the 1850s when sweetened condensed milk became available to Key West cooks who combined it with the abundant local Key limes. The result captures the essence of Florida’s laid-back coastal culture in a dessert that’s both sophisticated and approachable, representing the perfect marriage of convenience and tropical luxury.