Step 1

Preheat your oven to 180ºC/Fan 170ºC/356ºF and grease and line your tin. Melt the butter in a mixing bowl in the microwave in 10 second intervals.

Step 2

Beat in the sugar and cocoa powder with a spatula until it's no longer grainy on the bottom of the bowl.

Step 3

Add the eggs, vanilla and food colouring and beat until smooth and evenly coloured.

Step 4

Gently fold in the flour and salt, just until you can't see any more streaks of flour.

Step 5

Lastly, carefully stir through the white wine vinegar until evenly blended.

Step 6

Smooth the batter out into your prepared tin and bake for 23-25 mins until crisp on top. Allow to cool completely in the tin before removing and slicing.

Step 7

Melt white chocolate in the microwave in 10 second intervals. Once two thirds melted, stir until completely melted. Pour into a piping bag, snip the end and drizzle zig zags over each brownie. Allow to set on a cooling rack.