With layers of shortbread cookie crust, cloud-like lemon mousse, and tart lemon curd, this pie is both light and bright, and a great way to celebrate the upcoming arrival of spring.

Lemon Mousse Pie with Shortbread Crust from completelydelicious.com

Happy Pi (Pie) Day!

I’ve been saving this onesie just for today:


I haven’t always been on the Pi Day = Pie Day bandwagon, but this year I decided to hop on board. Why not? I always need another excuse to bake a pie.

Lemon Mousse Pie with Shortbread Crust from completelydelicious.com Lemon Mousse Pie with Shortbread Crust from completelydelicious.com
Lemon Mousse Pie with Shortbread Crust from completelydelicious.com

But what pie would I share with you? Since we’re still a few weeks out from spring produce I decided against a fresh fruit pie. But I still wanted something that tastes like almost spring and just hold on a little longer. And that for me, is lemon. It’s light and bright, and the perfect accompaniment to warmer weather and longer days.

Lemon Mousse Pie with Shortbread Crust from completelydelicious.com Lemon Mousse Pie with Shortbread Crust from completelydelicious.com
Lemon Mousse Pie with Shortbread Crust from completelydelicious.com

This recipe is a little fussy, I will admit that, although I did make quite a few changes from the original to make it easier. It starts with a tart lemon curd, and add to that gelatin, whipped egg whites, and whipped cream. And voila, you have yourself a lemon mousse that is downright heavenly.

The mousse is sandwiched between a crust of shortbread cookie crumbs and a lid of lemon curd. One bite and the memory of all that fuss will be gone. Totally worth it, I promise.

Lemon Mousse Pie with Shortbread Crust from completelydelicious.com

A few notes about this recipe:

>>The gelatin in this pie helps it firm up for easy and pretty slicing. If you are okay with a softer mousse and messier slices, feel free to omit this step.

>>If you’d rather, graham crackers make a fine substitution for shortbread cookies in the crust.

>>To make the cookie crumbs for the crust, place the cookies (or graham crackers) in a zipped plastic bag and crush with a rolling pin. Alternately, you can use a food processor.

>>If you’re new to the term “fold”, it is a method of gently incorporating egg whites into other ingredients without deflating them. This video shows you how to do it.

>>This recipe contains raw egg whites, as do all traditional mousse recipes. So are raw egg whites safe to eat? Well, salmonella can be found in 1 of 20,000 eggs so the risk is very small. However, if you’d rather avoid them, look into using pasteurized egg white substitutes or powdered egg whites. I have tried neither, so unfortunately I cannot say how well they will work in this recipe.

Lemon Mousse Pie with Shortbread Crust from completelydelicious.com

Lemon Mousse Pie
A light lemon mousse pie with shortbread crust and lemon curd topping.
Yield: 1 9-inch pie
  • 3 cups (about 300 grams) shortbread cookies, crushed (see Notes)
  • ¼ cup (56 grams) unsalted butter, melted
Lemon Curd:
  • ½ cup (113 grams) unsalted butter
  • 1 cup (200 grams) granulated sugar
  • 1 cup (235 grams) freshly squeezed lemon juice
  • 4 large eggs
  • 4 large egg yolks
  • ¼ cup (28 grams) cornstarch
  • 3 tablespoons water
  • 2 teaspoons (1 envelope) gelatin
  • Lemon curd (see above)
  • 4 large egg whites
  • ½ cup (100 grams) sugar
  • 1 cup (237 ml) heavy cream
To make the crust:
  1. Combine the shortbread cookie crumbs and butter. Press into an ungreased 9-inch pie dish. Bake at 350 degrees F for 10 minutes. Let cool completely.
To make the lemon curd:
  1. Combine the butter, sugar, and lemon juice in a medium saucepan over medium low heat. Stir to dissolve the sugar and melt butter. Heat until steaming, but not quite yet boiling.
  2. Meanwhile, whisk together the eggs and egg yolks with the cornstarch in a medium bowl. Slowly add the heated lemon juice mixture to the eggs in a slow and steady stream while whisking constantly. When fully combined, pour the mixture back into the saucepan.
  3. Place saucepan over medium heat and cook until mixture thickens, about 5 minutes, while whisking constantly. Pass lemon curd through a fine mesh strainer (to remove any lumps) into a small bowl or container. Place plastic wrap directly onto the surface of the curd and chill in the fridge for at least 1 hour. Lemon curd may be stored in the fridge for up to 1 week.
To make the mousse:
  1. Place the water in a small saucepan and sprinkle with the gelatin. Let sit for 5 minutes until gelatin is absorbed. Place over low heat and stir until gelatin is completely dissolved. Add ½ cup of the lemon curd and stir until mixture is smooth and all lumps are gone. Remove from heat and stir in another 1 cup of the lemon curd.
  2. In the bowl of a stand mixer fitted with a whisk attachment, or in a bowl with a hand-held mixer, beat the egg whites on high speed until foamy. With mixer on, slowly add sugar. Beat to stiff peaks. Gently fold the egg whites into the lemon curd mixture in 3 additions.
  3. Using the same bowl and whisk, beat the heavy cream on high speed to stiff peaks. Gently fold the whipped cream into the lemon mixture in 3 additions, careful not to deflate the mousse.
  4. Dump the mousse into the prepared pie crust and smooth the top. Spread the remaining lemon curd (should be about ½ cup) on top of the mousse. Chill in the fridge for at least 2 hours. Garnish with whipped cream and lemons before serving, if desired. Store leftovers in the fridge for up to 3 days.
Graham crackers may be substituted for the shortbread cookies, if desired.

Recipe adapted from Bon Appetit via Epicurious.

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16 Responses to Lemon Mousse Pie

  1. I seriously have no words to describe how amazing this pie looks! I am a huuuugeee lemon-lover and am totally a sucker for anything lemon-based so you can be sure this pie will be a good companion of mine for the rest of the spring/summer season!

    xo, Elisa

  2. This pie is stunning. I lover lemon meringue and can only imagine how good this version is!!

  3. Annalise,
    I haven’t gotten onto the Pi Day bandwagon either. Oh well, there’s always next year. Of course I pinned this. I’ve got to try it.

  4. Elaine says:


    I am still new to pie and am just on the way of learning. This one is so amazing. I will try this version.

  5. Kate says:


    I have been searching for not only a good pie recipe but also a lemon curd recipe. I made this today and I have to say thankyou your curd recipe is easy to make and fantastic to eat. I had too much mousse for the pie shell so I put the rest in glasses and ate it with strawberries for afternoon tea.

    Thanks for an amazing recipe

  6. It looks do tasty! I’ll be definitely making this when my lemon tree starts to fruit…which is hopefully very soon as I need this pie now.

  7. This looks amazing! I hope I have a chance to make your lemon mousse pie. Drop by sometime if you have time and your welcome to share at my weekly parties.

  8. Liren says:

    Annalise, this is one of the loveliest pies I have ever seen! The only thing that may beat it is that cutie patootie in that onsie!!!

  9. Slice says:

    I made this pie for a dinner with friends tonight and want you to know how much we enjoyed it. The curd recipe and method couldn’t have been easier–and so delicious. I took two shortcuts. I had regular pastry dough in the freezer so I blind baked that for the crust and I used bottled lemon juice rather than juicing all those lemons. It is organic, not-from-concentrate, nothing but pure lemon juice and it worked perfectly. Here’s a tip: to stabilize the whipped cream used for decorating the edge, I added a couple tablespoons of very soft cream cheese to the cream. The piped swirls held up beautifully for hours, even through dinner, unrefrigerated. And, I used pasteurized eggs for the whites. They seemed small, so I added one extra egg white and they take quite a bit longer to whip to stiff peaks, about eight minutes, a small price to pay for food safety. Delicious, keeper recipe!

    • Annalise says:

      So happy to hear you enjoyed the recipe! And thanks for sharing your shortcuts, I’m sure they’ll be helpful to others.

  10. Jenni says:

    Hi! I’m planning to give this amazing recipe a go but since it seems impossible to get your hands on cornstarch here in the UK I was wondering whether it would work to make the lemon curd without it completely for this exact pie as in many of the other lemon curd recipes? The only concern I have is whether the filling would turn out too runny, therefore turning the mousse and the top layer into something else entirely…

  11. gwen says:

    I love this pie I’ve made it twice and both times the lemon curd was too firm to put over the mousse evenly what am I doing wrong

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