Method

• 1.
  Roughly chop amaretti, tea biscuits and chocolate, then combine in a food processor and whiz until fine. Add cocoa and liqueur, stir through and set aside.
• 2.
  Beat sugar and butter in an electric mixer until pale, then beat in yolks one at a time. Add biscuit mixture, mixing well.
• 3.
  In a separate bowl, beat eggwhites to stiff peaks, then fold through the mixture.
• 4.
  Line a 25cm x 10cm loaf pan with plastic wrap. Split savoiardi, dip the cut sides of the sugary tops briefly in liqueur and use to line base, cut-side up, trimming to fit. Fill pan with the chocolate mixture. Level off and cover with the savoiardi bottoms (cut-side down). Cover with plastic wrap and freeze overnight.

• 5.
  For sauce, stir chocolate and butter in a heatproof bowl over a pan of simmering water (don't let bowl touch water) to melt. Add a dash more liqueur, then cool.
• 6.
  To serve cassata, turn out onto a platter, and remove plastic wrap. Dust with cocoa and cut into thick slices.
• 7.
  Serve with a drizzle of chocolate sauce.