Melt the chocolate, butter and golden syrup. Set a bowl over a saucepan of simmering water making sure not to let the water touch the bottom of the bowl. Place the butter, chocolate and Lyle's Golden Syrup into the bowl and stir until melted. Remove the bowl from the saucepan and set it to one side for the chocolate to cool slightly. Alternatively, place in a heatproof bowl and microwave for 10-second intervals stirring between bursts until melted.

Whisk the eggs and sugar. In a medium bowl, using a handheld mixer, whisk the egg, sugar and vanilla extract on high speed until pale and fluffy, for about 3 minutes. (This step can be done by hand- it might take a while though to achieve that pale yellow fluffy consistency that you are after!)Add chocolate. Whilst continuing to whisk on low, slowly pour in the melted chocolate then mix until just combined.

Sift in dry ingredients. Then sift into the mixing bowl the dry ingredients, flour, cocoa powder, and salt into the mixing bowl and fold through until a few flour streaks remain.

Add the chocolate. Add the milk chocolate chips and chopped white chocolate and fold through until evenly distributed throughout the batter.

Pour into pan and bake. Pour the batter into the prepared baking pan and smooth flat with an offset spatula. Bake for 25-30 minutes until set around the edges and a toothpick inserted into the centre comes out with a few moist crumbs. Cook for 5 more minutes if a more set centre is preferred. Remove from the oven and allow to cool in the pan for 15 minutes. Use the parchment paper sling to gently lift the brownies out of the pan and onto a wire rack to cool before cutting. Serve warm with a scoop of vanilla ice cream.