From their new book Perfect Pies, The Hairy Bikers' mini key lime pies mix a creamy texture with zingy citrus
300g sweetened condensed milk
200ml double cream
Finely grated zest and juice of 4 limes (you need 100ml of juice)
Lime syrup topping
50g caster sugar
200g chocolate digestive biscuits
200g dark chocolate sandwich biscuits, such as Oreos
You'll need 8 x 7.5cm deep fluted tartlet tins
To make the base, melt the butter in a small pan. Break the biscuits into chunks and put them in a food processor. Blitz into crumbs then add the butter and with the motor running, blend until thoroughly mixed. Alternatively, put the biscuits in a strong plastic food bag and bash with a rolling pin. Tip into a bowl and stir in the melted butter.
Divide the mixture between the tins and press firmly into the base and sides. Make sure the biscuit base is evenly distributed, especially where the base meets the sides and in between the flutes. Put the tins on a baking tray and chill for 30 minutes.
To make the filling, put the condensed milk and cream in a large bowl and whisk with electric beaters for about 3 minutes until light and soft peaks form. Whisk in the lime zest and fresh lime juice until the mixture thickens. Spoon into the biscuit cases and return to the fridge for 2–3 hours until set. Cover loosely with foil if leaving for longer.
To make the lime syrup for the topping, use a vegetable peeler to peel very fine strips of zest from half the lime. Cut the strips into 1mm matchsticks with a sharp knife. Squeeze the juice of the lime and put into a small saucepan with the water and any lime juice left over from the filling. Add the lime zest and bring to a simmer.
Cook for 5 minutes, stirring occasionally, until the lime zest is tender. Stir in the sugar, return to the boil and cook for a further 2–3 minutes until the sauce is syrupy, stirring every now and then. It will thicken a little as it cools too, so don’t reduce too much. Remove from the heat and leave to cool. Spoon a little of the lime syrup onto each tart. If the syrup has cooled and thickened too much, add a little water and warm it for a few seconds on the hob. Serve with single cream.
Tip: When you're ready to serve the tarts, lift them out of the tins very gently and slide them onto plates. You may need to use a palette knife to help you remove the tarts from the bases.
Recipe taken from The Hairy Bikers' Perfect Pies published by Weidenfeld & Nicolson