Method

• 1.
  For the butterscotch fudge glaze, place the caster sugar and 1/4 cup (60ml) water in a medium saucepan. Stir over low heat until sugar dissolves. Increase heat to high and cook, without stirring, for 6-8 minutes until sugar turns deep golden brown.
• 2.
  Remove pan from heat and whisk in the brown sugar and butter until combined. Return pan to low heat and whisk in the cream, being careful, as it will bubble up and splatter. Cook, whisking frequently, for 3-5 minutes until all crystallised sugar has melted and mixture is smooth and glossy.
• 3.
  Transfer to a large heatproof bowl, cover surface directly with plastic wrap and stand at room temperature until completely cooled and thickened.
• 4.
  Preheat oven to 200°C/180°C fan-forced. Grease a 25cm bundt pan.
• 5.
  To make the cake, place the cocoa and boiling water in a small heatproof jug and whisk until smooth. Set aside.
• 6.
  Place the sugar, flour, baking powder, bicarb and 1/2 tsp fine salt in a large bowl and stir to combine. Whisk milk, oil, eggs and vanilla extract in a large jug until combined, then stir into flour mixture until combined and smooth.
• 7.
  Transfer half the batter to a separate medium bowl, add cocoa mixture and stir until combined. Spoon one-third of the cocoa batter into base of the prepared pan, then add half the vanilla batter. Repeat layers, finishing with the cocoa batter.
• 8.
  Bake for 45 minutes or until a skewer inserted into the cake comes out clean. Line a wire rack with baking paper, then immediately invert cake onto the paper, leaving cake in pan. Stand for 15 minutes, then remove the pan and cool cake completely on rack.
• 9.
  Whisk cream, mascarpone and vanilla bean paste in a bowl until soft peaks form. Transfer cake to a serving platter, spoon over glaze and serve with vanilla cream.