20th anniversary ombré cake

Syrup

• 100 g caster sugar
• 1 lime, zest only, no white pith
• 120 g gin
• 10 juniper berries, crushed
• 80 g tonic water
• 1 lime, juice only

Four cake layers

• 445 g unsalted butter, softened and cut into pieces, plus extra to grease
• 400 g caster sugar
• 8 eggs, room temperature
• 4 tbsp milk
• 440 g self-raising flour
• natural green food colouring

Butter icing

• 500 g unsalted butter, softened and cut into pieces
• 700 g icing sugar
• 1 tbsp milk
• 1 tsp natural vanilla extract

Assembly

• natural green food colouring