Method

• 1.
  Preheat oven to 180°C/160°C fan-forced. Line the base and sides of a 22cm x 32cm x 3cm-deep slice pan with baking paper.
• 2.
  Place sugar and butter in a stand mixer fitted with the paddle attachment. Beat on medium-high speed for 1 minute, or until well combined. Scrape down side of bowl with a spatula.
• 3.
  Add the eggs, one at a time, beating until just incorporated and scraping down side of bowl. Add vanilla and beat until combined. Sift flour and cocoa directly into bowl and beat on low until starting to combine, then pour in oil and milk. Increase speed to medium-high and beat briefly until well combined and smooth.
• 4.
  Spoon mixture into prepared pan and level surface. Bake for 40-45 minutes, until a skewer inserted in the centre comes out clean. Cool cake in pan for 10 minutes, then transfer to a wire rack to cool completely.
• 5.
  Once cake has cooled completely, make the choc-marshmallow frosting. Place egg whites and sugar in a large heatproof bowl and whisk until just combined. Set bowl over a saucepan of simmering water over medium-low heat (don’t let base of bowl touch the water). Whisk constantly for 4-5 minutes, until sugar has completely dissolved and mixture is opaque and runny. Immediately transfer to the clean bowl of a stand mixer fitted with the whisk attachment and whisk on high speed for 8-10 minutes, until tripled in volume and firm peaks form. Sift over drinking chocolate and whisk until well combined.
• 6.
  Immediately spoon frosting all over cooled cake, creating small peaks. Set aside at room temperature for 30 minutes, or until frosting is firm, then use a kitchen blowtorch to toast the meringue frosting evenly. Slice and serve.