Key Lime Tart

This recipe can make a pie or a tart, it just depends how you want to present it! I’ve made it both ways. The tart is a bit more elegant presentation, if that’s important for your occasion.  I feel like you also might get more servings from a tart than a pie, but maybe that’s just how I slice it!  An all-time favorite in my house!

You can top it with meringue, whipped cream, or nothing at all!  The meringue recipe I use is has a couple more steps than most, but it turns out so fluffy and marshmallow-y, the extra step of making the cornstarch mixture is SO WORTH IT! It doesn’t deflate or weep, even if refrigerated.  If this is more work than you want, just whip your egg whites for a minute until foamy, then slowly add the sugar and continue to whip just until you see stiff peaks. Feel free either way to toast it in a 350F oven for 10-15 minutes or until browned as you like, or serve as is! Also wonderful without any topping for sure!

Note:  Raw or undercooked eggs can increase your risk of foodborne illness.  You should be aware of those risks, especially to those with lowered immunity.  

  • Author: Laura
  • Prep Time: 25 min
  • Cook Time: 25 min
  • Total Time: 50 min
  • Yield: 10 servings 1x
  • Category: Pies and Tarts
  • Method: Baking



For the Crust:

  • 12 Graham Cracker Sheets (24 squares)
  • 1 T Granulated Sugar (optional)
  • 7 T Unsalted butter, melted
  • 1/4 t salt

For the Custard:

  • 4 Large Egg Yolks
  • 114 oz. can Sweetened Condensed Milk
  • 5 oz. Key Lime Juice (or regular lime juice is perfectly substitutable!)
  • 1/2 t Cream of Tartar

For the Meringue:

  • 1/2 c Water
  • 1 T Cornstarch
  • 8 T Granulated Sugar, divided
  • 4 Lg Egg Whites
  • 1/4 t Cream of Tartar
  • Pinch Salt
  • 1/2 t Natural Vanilla


Make the Crust:

  1. Crush the graham cracker squares in a food processor or by placing them in a gallon-sized zippered bag, and crushing with a rolling pin.  Pour the crumbs, together with the (optional) sugar and salt, into a medium-sized bowl.
  2. Pour the melted butter into the crumb mixture and stir until it looks like wet sand.
  3. Press into a 9” tart pan, making sure the crumbs come up the side of pan about 1 1/2”.
  4. Bake in 350F oven for 10 minutes. Cool while you make the custard.

Make the Custard:

  1. In a stand mixer, or with a hand mixer, vigorously beat the egg yolks 5 minutes until they are thickened and light colored.  Lower mixer speed to medium-low, and slowly add the sweetened condensed milk until combined. While beating, add the lime juice and cream of tartar. Mix until completely combined.
  2. Pour filling into pie crust.  Return to oven for 13-17 minutes or until custard is firm and appears slightly dry. Remove to cool.

Make the Meringue:

  1. In a small saucepan, heat the water, cornstarch, and 2 T sugar over Medium-Low heat, stirring constantly until thickened.  This should take just 2-4 minutes. Mixture may remain slightly cloudy.  This is ok. Once mixture is thickened and smooth, remove from heat and let cool a bit while you whip the egg whites.
  2. Place egg whites, cream of tartar and salt into a metal bowl, attached to a stand mixer (hand mixer works too!). Mix on medium-high until nice and foamy.  Once whites are foamy, add the vanilla extract and slowly stream the remaining 6 T sugar and continue to whip until soft peaks are formed.
  3. Once the meringue is at the soft peaks stage, slowly stream or spoon in the cornstarch mixture and continue to whip until peaks are stiff.
  4. Pile meringue atop the custard.  If you want to toast it, place it over the warm custard and return it to the oven for 10-15 minutes or until it is browned to your liking.  I did not toast mine, rather, I refrigerated the pie for an hour before serving.  The meringue is actually best if served as is, without refrigeration.  This is good to know if you have any leftovers.


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