Step 1

Preheat oven to 170°C (150°C fan) mark

Step 2

Lightly grease a 22cm round fluted tart tin. Whizz biscuits in a food processor until finely crushed (alternatively bash in a food bag with a rolling pin). Add melted butter and pulse/mix until combined. Line base and sides of prepared tin with biscuit mixture. Press firmly in place with the back of a spoon. Bake for 10min.  Meanwhile, make the filling. Put egg yolks in a medium bowl, gradually whisk in condensed milk until combined. Whisk in lime zest and juice. Remove pie crust from oven and pour in filling. Return to oven for 8-10min until filling is set. Remove and cool on a wire rack. Meanwhile, make the candied lime slices. Heat sugar with 250ml water in a wide pan over low heat, stirring until sugar dissolves. Increase heat to medium-high, bring to boil, add lime slices in a single layer. Bubble for 10min, turning slices halfway through. Reduce heat; simmer gently for 15-20min, turning slices occasionally, until limes are tender and translucent (and sugar syrup remains clear). Remove slices with a slotted spoon to a baking sheet lined with baking parchment. Cool. Make the topping. Whip double cream and icing sugar to soft peaks. Cover and chill until needed. To serve, transfer pie to a cake stand or plate. Top with the whipped cream and candied lime slices. Serve in slices.