Finely grated zest and juice of 5 lemons
100g unsalted butter
6 large egg yolks
Make the macarons following the Foundation Macaron Recipe, adding yellow food colouring.
To make lemon curd, put zest, juice, butter and sugar in a heatproof bowl set over a saucepan of simmering water, making sure bottom of bowl does not touch water, until butter is melted. Take off heat and stir well. Add yolks and whisk continuously for 5 minutes or until mixture has thickened and coats the back of a spoon. Remove from heat and pour into sterilised jars. Refrigerate until cold.
Cook's tip: To sterilise jars for curds, line an oven tray with a damp wad of newspaper. Lay jars and lids on paper and put in oven for 20 minutes to sterilise.
Spoon lemon curd into a piping bag fitted with a 1cm plain nozzle. Pipe a little lemon curd onto 1 macaron, then sandwich with a second macaron. Repeat with remaining macarons and curd. Serve immediately, or arrange on oven trays and refrigerate or freeze overnight. Any leftover lemon curd can be stored in the fridge for up to 1 month.