Line your baking tray with grease proof paper. Place a glass bowl over a small pot of water and bring to boil. Place your chocolate into the bowl and slowly melt.

Add your butter to the chocolate and stir once fully melted. Set aside off the heat.

To the yolks add your sugar, essence (you can use vanilla essence if you don't have orange) and flour (use ground almond for a gluten free version).

Mix to combine to a thick paste. Set aside.

Whisk the egg whites to stiff meringue. See tip for a quicker meringue.

Add your still warm chocolate into the yolk sugar mixture and combine well.

Gently and slowly fold in the egg whites a third as a time until combined.

Put your marmalade into a pot with 1 tbsp water and heat until melted and the consistency of runny honey. Once melted pour over the chocolate mixture.

Using a butter knife or back of a tablespoon swirl the marmalade into the chocolate. Sprinkle over a little sea salt.

I decorated with Jaffa cakes but this is optional. Place in the preheated oven for 25-35 minutes. Brown is done when a knife comes out clean.

Allow to cool completely before slicing into squares.