Preheat oven to 350F (180C). Grease and line with parchment paper two 9x5in (23x13cm) loaf pans.

Place butter in a sauce pan and melt over low heat. Add sugar, cocoa powder and milk and stir to combine. Bring to a boil for 1 minute.Remove from heat.

To make the chocolate glaze for the top place the chocolate pieces into a small bowl and add about 1 cup (220g) of the hot cocoa syrup. Stir to melt the chocolate and set aside until ready to use.

While the cocoa syrup cools down slightly separate the egg whites from yolks and whip the egg whites until foamy and stiff peaks form.

Incorporate yolks one at a time then add flour, salt and baking powder to the cocoa syrup and stir to combine. Gently fold the whipped whites into the mixture and divide mixture evenly into the prepared pans.

Bake for about 30-35 minutes until a toothpick inserted in center of cake comes out with a few moist crumbs attached.

Pour the reserved chocolate glaze on the top and decorate with nuts if desired.

Let cool completely before serving.