Tiramisú layer cakes

Preheat oven to 170C. Beat butter and sugar in an electric mixer until pale and fluffy (2-3 minutes). Add egg, beat well. Sift over flour and baking powder, stir to combine, add espresso and milk and stir to combine. Spread in a greased and baking paper-lined 26cm x 35cm baking tray, smoothing top. Bake until golden and cake springs back when lightly pressed with fingertip (15-20 minutes), cool completely on a wire rack.

Meanwhile, for espresso syrup, stir sugar and espresso in a small saucepan over medium-high heat until sugar dissolves. Bring to the boil, remove from heat, stir in liqueur, cool to room temperature and set aside.

Meanwhile, for whipped mascarpone, whisk egg yolks and sugar in a bowl until pale and creamy (1-2 minutes), add mascarpone. Whisk until thick and smooth (don't overwhisk), spoon into a piping bag (no nozzle), refrigerate until required.

To assemble, place six 6cm-high, 5.5cm-diameter cake rings (see note) on a baking paper-lined tray. Cut eighteen 5.5cm-diameter rounds from cake and place a cake round in the base of each mould. Brush with syrup, pipe a 5mm layer of whipped mascarpone on top. Dust with cocoa, top with another cake round and brush with syrup. Repeat until you've used all cake rounds, finishing with a layer of mascarpone. Cover and refrigerate for 2 hours.

To serve, run a small knife dipped in hot water around rings and remove. Dust tops of cakes with cocoa, serve immediately with extra espresso syrup if desired. Cakes will keep for up to 3 days in an airtight container in the refrigerator.