Colin's gooey chocolate biscuits

Method

• 1
  For the dulce de leche, preheat oven to 220C/200C fan forced. Pour the condensed milk into a heatproof baking dish. Place the dish in a roasting pan. Pour water into the pan to come halfway up the side of the dish. Cover with foil and bake, refilling the pan with water if necessary, for 1 hour 45 minutes or until dark golden. Whisk until smooth. Cool.
• 2
  Meanwhile, grease 2 baking trays and line with baking paper. Use electric beaters to beat the butter and sugar together in a large bowl until pale and creamy. Beat in the egg yolks. Use a large metal spoon to fold in the flour and cocoa until the mixture comes together. Turn onto a clean work surface and knead lightly until smooth. Enclose in plastic wrap. Place in the fridge for 30 minutes or until firm.
• 3
  Roll one-third of the dough out between 2 pieces of baking paper until thin. Use a 4cm round cutter to cut 30 discs from the dough. Place on prepared trays.
• 4
  Put a few pieces of the chocolate in the middle of each disc. Top with 1⁄2 tsp dulce de leche. Roll out the remaining dough. Use a 5cm round cutter to cut 30 discs from the dough. Place the larger discs on top of the smaller. Press gently to seal. Place the trays in the freezer for 10 minutes to rest.
• 5
  Preheat the oven to 190C/170C fan forced. Bake for 10 minutes or until crisp. Serve hot or cold.