Chocolate and nut babka

Brioche

• 60 g unsalted butter, plus extra melted to grease
• 180 g full cream milk
• 60 g white sugar
• 1 tsp dried instant yeast
• 450 g baker's flour, plus extra to dust
• 1 tsp sea salt
• 2 eggs
• 150 g hazelnut chocolate spread, room temperature (see Tips)

Chocolate sauce

• 80 g water
• 50 g Dutch cocoa powder
• 80 g hazelnut chocolate spread
• 100 g pouring (whipping) cream
• walnut halves, toasted, to garnish