The Best Key Lime Pie with Biscoff & Graham Crust

Aside from cheesecake, key lime pie is one of my most requested desserts! Even more than chocolate! To be honest, I thought that key lime pie would be daunting to make partly because I knew I liked it but didn’t know what it was made with. What is this mysterious, delicious custardy lime filling? Sounds silly maybe but I’m just used to making cakes or fruit pies at home. Turns out, it’s way easier and more straightforward than many of the desserts I make.

I was scouring the internet for a recipe that resonated with me, that had good reviews etc.. You know, as one does. I thought I’d found the one until Claire Saffitz, the dessert queen, published a video on YouTube for guess what? Key Lime Pie and when Claire develops a recipe it’s always on point and she thinks of everything. The pie, as she claims is neither too sweet or too tart. She also adds cream cheese to the whipped cream topping to stabilize it. Meaning it keeps your whipped topping from flopping after a day in the fridge. Having experienced this issue with my attempt at Banoffee, I was into this solution. It worked! My topping kept for 3 days. It may have lasted beyond that but… we ate it lol

My contributions to this recipe are as follows. Instead of cream cheese, I used Mascarpone because that’s what I had in my fridge and it works interchangeably. I’d love to try it with Philadelphia cream cheese as I would love to see if it adds a cheesecake-ishness (a word often spoken but seldom written) flavour. My second contribution is adding crushed Lotus-Biscoff cookies to my graham crumbs. It’s not necessary but they add a deeper caramel flavour and because you’re crushing them in a resealable bag or in a food processor, you will get a mix of crumb sizes, creating texture, of which I am a big fan.

Citrus desserts can be enjoyed all year round but in summer, you can especially appreciate them. When it’s warm, you want something cool and bright, sweet and tart and key lime pie is just that.

Note: If you can’t find key limes or if you prefer not to use them because juicing them can be a little tedious, you can use regular limes! YAY!

Side note: I once made a Margarita Pie & It was so good and similar to key lime pie & yes, it contains tequila! Want me to find it and share it? Let me know in the comments!

I hope you enjoy this recipe!

Recipe based on Claire Saffitz’s recipe.

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The Best Key Lime Pie with Biscoff-Graham Crust

Print Recipe
Bright, not too sweet and not too tart. With a light whipped topping. Appropriate for summer but can be enjoyed at any time of the year. What makes this different? I blend Lotus Biscoff cookies into my graham crust for added texture and depth! I also add a little mascarpone to my topping so the cream holds its structure better. It’s great & I hope you love it too!


  • 9” Pie plate
  • Hand mixer or whisk



  • 100 g graham crumbs
  • 70 g Lotus Biscoff classic cookies (not the sandwich ones) Pulsed in a food processor or crushed in a resealable bag with a rolling pin until you get fine crumbs. Uneven bits are ok. – See note
  • 5 tbsp unsalted butter melted and cooled.
  • 2 tbsp granulated sugar
  • 1 large egg yolk
  • ½ teaspoon kosher salt


  • 1 tbsp freshly grated lime zest
  • 5 large egg yolks
  • 1 300 ml can sweetened condensed milk
  • ¾ cup fresh lime juice strained
  • Pinch of salt
  • 1 teaspoon vanilla extract


  • 1/4 cup mascarpone cheese at room temperature (or cream cheese)
  • 2 tablespoons powdered sugar
  • 1 cup heavy cream chilled
  • More fresh lime zest for serving


PREHEAT THE OVEN: Arrange an oven rack in the center position and preheat the oven to 350°F.


    • Pulse Biscoff cookies in a food processor until finely ground, but it’s very doable by hand. Transfer the graham and Biscoff crumbs to a medium bowl and add the melted butter, granulated sugar, yolk, and salt. Toss with a fork until the mixture is well combined, then rub the mixture with your fingertips until it looks like wet sand.
    • PRESS IN THE CRUST AND BAKE: Transfer the mixture to a 9-inch pie plate and scatter the crumbs evenly across the bottom. Use a straight-sided glass or 1-cup dry measure to very firmly press the mixture up the sides of the plate and across the bottom, flattening it into an even layer. Place the plate on a sheet pan and bake until the crust is fragrant, firm to the touch, and dark brown around the edges, 8 to 12 minutes. Remove from the oven and let cool while you make the filling.
    • 👀REDUCE THE OVEN TEMP: Turn the oven down to 325°F.
    • MAKE THE FILLING AND BAKE: In a medium bowl, combine the zest, yolks, sweetened condensed milk, lime juice, salt, and vanilla and whisk until completely smooth. Pour the filling into the pie plate and smooth the surface. Transfer the pie back to the oven and bake until the filling is set and just a little wobbly in the center, 15 to 20 minutes. Remove from the over and let cool completely at room temperature, about 1 hour, then transfer to the refrigerator and chill until cold, at least 2 hours.
    • MAKE THE TOPPING: In a medium bowl, combine the mascarpone cheese and powdered sugar and work the mixture with a flexible spatula until the sugar is completely incorporated and the cheese is smooth. Add the cold cream, whisking to incorporate or you can use a hand mixer. Slowly add the cream, whisking constantly to prevent lumps, until you have a thick, smooth mixture, then whisk vigorously until you have a softly whipped cream that forms medium peaks.
    • Remove the pie from the refrigerator and scrape the whipped cream onto the surface, spreading it nearly to the edges. Return to the fridge and chill just until the topping is set, at least 15 minutes.
    • SERVE: Top the pie with fresh lime zest, cut into slices, and serve.



    DO AHEAD: The pie can be baked and chilled (without the topping) 1 day ahead. When it’s cold, cover loosely with plastic wrap, then top within a couple of hours of serving. Any leftover pie will keep, covered with plastic, for several days in plastic for several days.
    THE CRUST:  I really love the mix of graham and biscoff for extra depth, flavour and texture but you can use the full 170g of graham crumbs or if you want added texture, pulse graham crumbs in a food processor.
    Instead of pulsing in a food processor, you can place the cookies in a resealable bag and crush them with a rolling pin. 
    My crumb mixture felt looser than when I use just graham but that’s ok, my pie crust baked up perfectly and it didn’t disintegrate when I cut into it, so don’t worry.

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