Lime Mousse Pie

This isn’t a key lime pie and it isn’t a cheesecake. It’s something cooler and lighter, a frozen lime mousse built on an angel food cake base that drinks up a splash of rum before the mousse goes on top. When it comes out of the freezer, you get the tang of fresh lime against the pillow softness of a three-part mousse: gelatin-set yolk base, whipped cream Chantilly, and stiff egg whites folded in last.

The three-stage folding is what makes this thing float on the plate. Each addition aerates the mix further, so the mousse sets airy rather than heavy. The yolk-lime-gelatin base goes in first, chilled. Then the whipped cream folds in to smooth it out. Last, whipped egg whites fold in gently to push volume up to cloud-level.

A thin slice of angel food cake under the mousse catches all the juices and liqueur, acting like a sponge for the flavor while giving you something to cut against with a fork.

Pro Tips

• Bloom gelatin leaves in cold water first, wring them out, then dissolve in hot water. Dumping them straight in leaves stringy bits.
• Use fresh-squeezed lime juice, not bottled. Bottled lime juice tastes tinny and ruins the mousse.
• Whip cream only to soft peaks. Overwhipped cream seizes into butter when you fold it into the gelatin mix.
• Transfer the pie from freezer to fridge 6 hours before serving. That slow thaw keeps the mousse from crystallizing.

Variations

• Swap lime for lemon or passionfruit for a different citrus profile.
• Use a digestive biscuit or graham cracker crust if you don’t have angel food cake on hand.
• Top with fresh berries and mint before serving for a bright finish.