83% would make this again

Key Lime Pie Mousse

Q: Can I use regular limes instead of Key limes?

Yes. Fresh Persian limes work well and many bakers prefer them over bottled Key lime juice. Fresh Key limes still give the most traditional flavour, but regular limes are a great, easy swap.

Q: Is bottled Key lime juice OK?

It works in a pinch, but fresh juice usually tastes brighter and less artificial. Taste tests and side-by-side bakes tend to favour fresh juice for a cleaner, more floral lime flavour. Try to use fresh organic Limes for the best results.

Q: Why isn’t my Key lime dessert green?

Because real Key lime filling is naturally pale yellow. If you see a bright green dessert, it got that colour from food colouring, not from the limes.

Q: Why didn’t my filling set?

For classic pie, the acid in lime juice thickens the egg yolks and condensed milk, and gentle baking helps it hold a clean slice; using the wrong milk (like evaporated) or under-baking can keep it loose. For a mousse, you need proper soft-peak whipped cream and enough chill time; if you add a jelly top, be sure the mousse is cold before you pour it on.

Q: Can I make it vegetarian without gelatin?

Yes. Agar works, but it sets firmer and less creamy than gelatin. Boil agar to dissolve it fully, use the right strength, and expect a slightly different bite compared with gelatin.

Q: How far ahead can I make it and how do I store it?

The crumb base and mousse can be assembled a day ahead. Keep glasses covered in the fridge, add the jelly top once the mousse is cold, and finish with zest right before serving. Leftovers keep well in the fridge for about two days; freeze is not ideal because the mousse can lose its silky texture.

Vish G

August 28, 2025

Key Lime Pie Mousse is a light and refreshing take on the classic pie. The buttery biscuit base, smooth mousse, and tangy lime jelly layer make every spoonful taste bright and balanced. Simple to prepare yet impressive to serve, it’s a dessert everyone will love.

PREP TIME

25 MIN

COOK TIME

5 MIN

SERVINGS

Ingredients

For the Biscuit Base
150g (about 1 ½ cups) digestive biscuits or graham crackers, crushed
75g (5 tbsp) unsalted butter, melted
1 tbsp sugar (optional, for extra sweetness)
For the Mousse Layer
300ml (1 ¼ cups) double cream or heavy cream
200g (about ½ can) sweetened condensed milk
80ml (⅓ cup) fresh lime juice (key limes or regular limes)
1 tbsp lime zest
1 tsp vanilla extract
For the Jelly Top
200ml (¾ cup + 2 tbsp) water
50ml (3 tbsp) fresh lime juice
2 tbsp sugar (adjust to taste)
2 leaves gelatine or 1 tsp powdered gelatine (or agar-agar as a vegetarian option)
A drop of green food colouring (optional, for a pale green finish)
For Garnish
Fresh lime zest or curls
Extra biscuit crumbs or a thin lime slice

Instructions

Crush the biscuits into fine crumbs and mix with melted butter and sugar if using. Spoon into the bottom of each glass and press down gently with the back of a spoon. Place in the fridge to set.
In a large bowl, whisk the cream until it reaches soft peaks. In another bowl, stir together condensed milk, lime juice, lime zest, and vanilla. Gently fold the whipped cream into this mixture in two or three batches until smooth and airy.
Spoon or pipe the mousse evenly over the chilled biscuit base. Smooth the tops and return to the fridge to set while you prepare the jelly.
Soak gelatine leaves in cold water for 5 minutes, or if using powdered gelatine, sprinkle it over 2 tbsp cold water in a small bowl and let it sit for 5 minutes.
Heat 200ml water and sugar in a small pan until just warm and the sugar dissolves. Remove from the heat and stir in lime juice. Squeeze out the gelatine leaves and stir them in until dissolved (or stir in the bloomed powdered gelatine).
Add a drop of green food colouring if you like. Let cool until just lukewarm.
Slowly spoon the cooled jelly over the mousse layer in each glass. Return to the fridge and chill for at least 3–4 hours until fully set.
When ready to serve, top with a little lime zest, a curl of lime peel, or extra biscuit crumbs for decoration.