500 gmstrong baker's flour25 gmfresh yeast (or 14gm dried yeast; 2 sachets)25 gmcaster sugar1 tspsalt6eggs50 mlmilk250 gmbutter, softened1egg, beaten with a splash of milkChocolate filling150 gmdark chocolate, coarsely chopped (or buttons such as Valrhona Manjari Feves)50 gmcaster sugar75 gmroasted blanched almonds125 ml(½ cup) pouring cream1 tspvanilla extract
Place the flour, yeast, sugar and salt in an electric mixer fitted with a dough hook and mix on low speed to combine. Add the eggs, then the milk, and mix on medium until a smooth dough forms and is no longer sticking to the sides of the bowl.
Once the dough starts to become elastic, add the butter in 3 separate lots, ensuring each is completely mixed in before adding the next.
Place the dough in a bowl greased with spray or olive oil and set aside to prove for 45 minutes, then knock the dough back and refrigerate overnight (you can skip the first proving step and refrigerate the dough straightaway if you're short on time).
For the chocolate filling, place the chocolate in a food processor and pulse until crumbs form. Add the almonds and blend again for another 10 seconds until the mixture resembles fine breadcrumbs (the oil will start to come out of the almonds and form a paste). Add the sugar, blend to combine, then add the cream and vanilla and blend until the mixture becomes smooth (it doesn't need to be too fine). Refrigerate overnight while your brioche is proving.
Preheat oven to 190C and bring chocolate filling to room temperature. Tip the dough out onto a lightly floured bench. Using your hands or a rolling pin, flatten the dough into a rectangle around 60cm x 25cm with the longest edge facing you. Spread the chocolate mixture over the dough, then make a book fold to envelope the chocolate by folding each end to meet in the centre, then folding it in half lengthways. Cut the dough into 4cm pieces and place on an oven tray lined with baking paper. Allow the brioche to prove for 20 minutes, then brush with eggwash and bake for around 20 minutes until golden.