Lemon Mousse Shortbread Cups (Printable)

Zesty lemon mousse paired with buttery shortbread crumble for a light, refreshing spring treat.

# What You Need:

→ Shortbread Crumble

01 - 1 cup all-purpose flour
02 - 1/4 cup granulated sugar
03 - 1/2 cup unsalted butter, cold and cubed
04 - Pinch of salt

→ Lemon Mousse

05 - 3 large eggs, separated
06 - 1/2 cup granulated sugar
07 - 1/3 cup freshly squeezed lemon juice
08 - 2 teaspoons finely grated lemon zest
09 - 1/2 cup heavy cream, chilled
10 - 1/4 teaspoon cream of tartar

→ Garnish

11 - Fresh berries
12 - Lemon zest curls
13 - Fresh mint leaves

# Steps:

01 - Preheat the oven to 350°F. Line a baking sheet with parchment paper.
02 - In a bowl, combine flour, sugar, salt, and cold cubed butter. Rub together with your fingertips or use a pastry cutter until mixture resembles coarse crumbs. Spread evenly on the prepared baking sheet.
03 - Bake for 12 to 15 minutes, stirring halfway through, until golden brown. Cool completely.
04 - In a heatproof bowl, whisk together egg yolks, 1/4 cup sugar, lemon juice, and lemon zest. Place the bowl over a pot of simmering water and whisk constantly until thickened, approximately 7 minutes. Remove from heat and cool to room temperature.
05 - In a clean bowl, beat egg whites with cream of tartar until soft peaks form. Gradually add remaining 1/4 cup sugar and beat until stiff peaks form.
06 - In a separate bowl, whip the chilled cream to soft peaks.
07 - Gently fold the whipped cream into the cooled lemon mixture. Then fold in the egg whites until just combined and smooth.
08 - Spoon a generous layer of shortbread crumble into the bottom of 6 small serving glasses or ramekins. Top with lemon mousse.
09 - Chill for at least 2 hours before serving. Garnish each cup with fresh berries, lemon zest curls, and mint leaves if desired.

# Expert Tips:

01 -
  • The contrast between the buttery, crumbly base and silky mousse is genuinely addictive and feels restaurant-quality without the fuss.
  • It comes together in under an hour of actual work, then does most of the heavy lifting in the refrigerator while you relax.
  • You get to use a double boiler, which somehow makes you feel like you actually know what you're doing in the kitchen.
02 -
  • The double boiler step genuinely matters—I learned this the hard way when I tried to speed things up with direct heat and ended up with scrambled egg bits floating in lemon juice instead of a silky curd.
  • Room temperature matters more than you'd think; if you fold warm lemon mixture into your whipped cream and egg whites, the heat collapses all that air you worked to create.
  • These actually taste better the next day when the mousse has set completely and the flavors have had time to meld together.
03 -
  • Make the crumble a day ahead and store it in an airtight container—it stays crispy and you only have the mousse to worry about on serving day.
  • If your egg whites won't beat into stiff peaks, they probably had a speck of yolk in them; even a tiny amount of fat prevents proper foaming, so it's worth starting fresh with a clean bowl.
  • These cups actually freeze beautifully for up to a month, which means you can assemble them whenever you want a fancy dessert that doesn't require same-day work.
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