Key Lime Bars with Mango Topping

key lime mango bars

Ah, key lime pie. It’s one of my husband’s favorite desserts, so I’ve spent time fiddling with the recipe in search of my ideal version. If I’m being honest, I’ve always found key lime pie…hmmmm, a little lacking? Now I wouldn’t turn down a slice, but the classic proportions feel off (not enough filling to crust, but if you double the filling it’s overload) and I get bored after a couple bites.

So, you fiddle. I’ve tried adding different dairy products, folding in egg whites, etc. but in the end I think the classic egg yolks + condensed milk + lime juice + zest can’t be beat for its combination of ease and taste. (But I do beat the egg yolks really well to get a nice airy texture.) I also prefer baking the pie as bars in an 8×8 pan for what I think is a better crust to filling ratio. Bonus: it’s also easier to slice.

And finally, I like to add some sort of extra layer. This time around I went with a mango gel layer for some color and sweetness; and I loved it! But you could go with straight lime curd to really lean into the tartness; and of course good old whipped cream is always a safe option. I also think a fresh berry layer could be fun! (I didn’t say I was done fiddling, did I?)

Whatever you choose, these key lime bars are a great, simple, make-ahead dessert anytime of the year. Enjoy!

Baker’s Notes:

  • I typically use regular old limes for the filling because juicing a couple dozen tiny key limes feels like punishment. Yes, that makes them lime bars instead of key lime bars. Oh well.
  • I don’t find my bottom crust gets too soggy even after a few days in the fridge (it does soften, but not in an unpleasant way). But if you want extra insurance, you can brush the baked crust with a layer of egg white and return it to the oven for 1-2 minutes. Then pour in your filling and bake as directed.
  • I am staunchly on team canned mango puree (or pulp). The texture, consistent flavor, and convenience is totally worth it for me. I buy either alphonso or kesar varieties at my local grocery store (look in the international aisle). You can also find it online. Look for something that has just mango pulp, sugar (or sugar syrup or sugar and water), and citric acid as the ingredients. Canned puree is typically lightly sweetened; so if you’re making your own puree you may need to add additional sugar to taste.
key lime mango bars

Key Lime Bars with Mango Topping

Yield: One 8x8 pan
Prep Time: 30 minutes
Cook Time: 25 minutes
Additional Time: 4 hours
Total Time: 4 hours 55 minutes


For the graham cracker crust:

  • 175g graham cracker crumbs
  • 12g granulated sugar
  • Pinch of kosher salt
  • 56 g unsalted butter, melted

For the key lime filling:

  • 5 large egg yolks
  • 1 Tbsp lime zest (from 3-4 regular limes)
  • 1 14-oz can sweetened condensed milk
  • 170g freshly squeezed lime juice (from 6-8 regular limes or about 20 key limes)

For the mango topping:

  • 35g cold water
  • 7g powdered gelatin (2 1/4 tsp or 1 packet)
  • 270g mango purée (I used canned and lightly sweetened)
  • 5g lime juice
  • 12g granulated sugar (might need to increase if using homemade purée)


  1. Make the graham cracker crust: Preheat the oven to 350°F (175°C) with one
    rack in the middle and one below. Line an 8-inch square pan with at least 2-inch (7.5-cm) sides and line with two criss-crossed pieces of parchment paper, leaving about 2 inches (7.5 cm) of overhang on all sides for easy
    removal. Lightly grease the pan and parchment
  2. Stir together the cracker crumbs, sugar, salt, and melted butter. The mixture should hold together if you squeeze it in your hand, but shouldn’t feel overly greasy. If the mixture doesn’t hold together, add more melted butter 1 teaspoon at a time until it does. If overly greasy, add more cracker crumbs, 1 teaspoon at a time, until you get the right texture.
  3. Press the cookie crumbs into the bottom of
    the pan, using a measuring cup or shot glass to compact the crumbs firmly and
  4. Bake until just set, about 10 minutes. Allow to cool on a wire rack while preparing the filling.
  5. Make the key lime filling: Place the egg yolks and lime zest in a medium bowl. Using an electric handheld mixer, whisk together on medium speed until well combined. Add the condensed milk and whisk on medium to medium-high speed until pale and thickened, about 3 minutes. Add the lime juice and mix on low speed until combined.
  6. Scrape the filling into the prepared crust and gently shake side to side to level. For the smoothest top, bounce a spoon over the top of the filling to bring up and pop any air bubbles that might be trapped in the filling.
  7. Bake for 10-13 minutes, or until the center has just a slight jiggle. Cool at room temperature for an hour, then refrigerate uncovered for one hour before preparing the mango topping.
  8. Make the mango topping: Pour the cold water into a small, shallow bowl. Sprinkle the gelatin evenly over the surface and allow to bloom for 5-10 minutes.
  9. In a small saucepan, whisk together the sugar, 70g mango purée, and lime juice. Set over medium heat and cook, stirring frequently, until just steaming. Turn off heat, add bloomed gelatin, and whisk until dissolved. Add remaining 200g mango purée.
  10. Carefully pour the mango topping onto the chilled bars. Use a skewer to pop any air bubbles. Refrigerate to set, at least 3 hours or overnight, before slicing.
  11. Refrigerate leftovers in an airtight container for up to 5 days. (The crust will soften with time.)

key lime bar with mango fork