Gruyère, mozzarella and thyme brioche buns

Method

1. Put the yeast, sugar, flour, thyme and salt in a stand mixer. Make a well in the middle and pour in the milk and the 4 beaten eggs, then mix with the dough hook for 10 minutes until the mixture forms a stretchy dough. Switch the attachment to the paddle, then add the butter, beating it in a knob at a time, making sure each is incorporated before adding the next. When all the butter has been mixed into, put the dough in a large, lightly oiled mixing bowl, cover with cling film and leave to rise in a warm place for about an hour or until doubled in size.
2. Line a baking sheet with non-stick baking paper. Mix together the two cheeses in a small bowl. Gently knead the dough on a lightly floured surface to knock out any large air bubbles – don’t overwork it. Divide into 10 pieces (about 80g each).
3. Roll each piece of dough into a ball, then flatten with your hand. Put 15g of grated cheese into the centre and bring the edges up around the cheese, pinching to enclose. Put each dough ball on the work surface, seam-side down, and gently roll it under one cupped hand to give it a spherical shape. Put the bun onto the prepared baking sheet and repeat with the remaining dough, placing the buns about 10cm apart from each other.
4. Brush the buns with the remaining beaten egg and scatter over the remaining cheese, extra thyme and the sea salt. Set aside at room temperature, loosely covered with oiled cling film, to prove for 30 minutes. Heat the oven to 200°C/180°C fan/gas 6.5 Bake the buns for 25 minutes until golden and risen. Leave to cool for 15-20 minutes, then serve warm.