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Creamy key lime pie bars featuring a salty miso-infused graham cracker crust and fresh lime zest.

Silky Key Lime Pie Bars

Rebecca Blumer
These silky key lime pie bars feature a tart, creamy posset filling and a crisp graham cracker crust for the ultimate balance of sweet and citrusy sunshine in every bite.
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Prep Time 20 minutes
Cook Time 15 minutes
Cooling and Chilling 6 hours 10 minutes
Total Time 6 hours 45 minutes
Course Dessert
Cuisine American
Servings 16 bars
Calories 285 kcal

Equipment

  • 8-inch square baking pan
  • Parchment Paper
  • Large saucepan
  • Microplane or zester

Ingredients
 

Filling:

  • 568 g heavy cream
  • 149 g granulated sugar
  • 1/8 teaspoon table salt
  • 1 zest of lime
  • 85 g Key lime juice

Crust:

  • 150 g graham cracker crumbs
  • 28 g confectioners' sugar
  • 1/8 teaspoon table salt
  • 85 g unsalted butter, melted

Topping:

  • 113 g whipped cream
  • 1 zest of lime

Instructions
 

Prep the Pan and Get Ready

  • Preheat your oven to 350°F (175°C) with the rack positioned in the center. Line an 8-inch square baking pan with parchment paper, ensuring there is extra overhang on two sides to act as a sling for easy removal.
  • Zest the limes before juicing them. Prepare a fine-mesh strainer to ensure the juice is free of seeds and pulp.

Cook the Posset-Style Filling

  • In a large saucepan over high heat, combine the heavy cream, granulated sugar, table salt, and lime zest. Stir occasionally until the sugar is fully dissolved.
  • Bring the mixture to a boil, then reduce the heat slightly to maintain a gentle boil for exactly 5 minutes, stirring constantly to prevent foaming over.
  • Remove the saucepan from the heat and stir in the Key lime juice until the mixture becomes silky and emulsified. Let it cool slightly in the pot while you prepare the crust.

Build, Bake, Cool, Then Chill to Set

  • In a medium bowl, combine the graham cracker crumbs, confectioners' sugar, and salt. Stir in the melted butter until the mixture resembles damp sand. If using miso, whisk it into the butter before adding to the crumbs.
  • Press the crumb mixture firmly into the bottom of the prepared pan, using a flat-bottomed cup to ensure an even, compact layer.
  • Bake the crust for 10 to 15 minutes until it is lightly toasted. Let the crust cool on a wire rack for 10 minutes before adding the filling.
  • Pour the lime filling over the slightly cooled crust. Refrigerate uncovered for at least 6 hours, or ideally overnight, until the bars are completely set and firm.
  • Lift the bars out using the parchment sling. Slice into squares using a hot, dry knife, cleaning the blade between each cut for sharp edges.
  • Top each bar with a dollop of whipped cream and a final sprinkle of lime zest just before serving.

Notes

Structure Secret: The 5-minute boil is essential for the cream to set correctly once the lime juice is added. Do not cut this time short or the filling may remain liquid.
Clean Cutting Tip: For bakery-style sharp edges, dip your knife in hot water and wipe it completely dry before every single slice.
Storage Instructions: These bars can be stored in the refrigerator for up to 4 days. For long-term storage, freeze the bars without the whipped cream topping for up to 3 months, then thaw in the fridge.
Preparation Tip: Always zest your limes before juicing them. Once a lime is squeezed and softened, it becomes nearly impossible to zest cleanly.
Nutrition information is estimated based on common ingredients and serving sizes and may vary.

Nutrition

Calories: 285kcalCarbohydrates: 24gProtein: 2gFat: 21gSaturated Fat: 13gCholesterol: 65mgSodium: 125mgPotassium: 68mgFiber: 0.5gSugar: 17gVitamin A: 720IUVitamin C: 4mgCalcium: 45mgIron: 0.6mg
Keyword citrus dessert, key lime pie bars, posset bars
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