Brioche is a rich yeast bread that contains lots of butter and eggs. Some say it was first made in Brittany, while others claim it is from Normandy, but it has been baked in Paris since the 17th century.
To make the dough, sprinkle the yeast and one teaspoon caster sugar on to the warm milk in a small bowl. Whisk lightly, then leave in a warm place for 10 minutes or until a light foam forms on the surface.
Sift the flour, salt and two tablespoons of caster sugar into a large mixing bowl. Make a well in the centre and pour in the yeast mixture and beaten eggs. Mix with a wooden spoon until it forms a ball.
Turn the dough out on to a floured surface and knead it gently for about 5 minutes until smooth.
Gradually add the softened butter, a teaspoon at a time, kneading well in between each addition. It will take about 10 minutes to incorporate the butter and the dough will be sticky. Flour the surface generously as you knead in the butter.
On a clean floured surface and using clean hands, sprinkle the dough with more flour. Continue to knead lightly for a further 10 minutes or until the dough is very pliable, smooth and slightly shiny but no longer sticky.
Place the dough in a large lightly oiled bowl and cover with oiled cling film. Leave in a warm place for 1½ hours until well risen and spongy.
Put the pralines a few at a time in a pestle and mortar and crush them roughly. Some will become powdery but you should have some larger chunks too. Tip them into a bowl as soon as each batch is done. Set aside.
Oil a 23cm/9in spring-clip cake tin and line the base with baking parchment.
Turn the dough out on to a lightly floured surface and knock it back with your knuckles. Knead for a minute or so, then roll it out with a floured rolling pin to make a square measuring 35cm x 35cm/14in x 14in.
Sprinkle the crushed pralines over the top, taking them all the way to the edge.
Roll the dough up like a Swiss roll and cut it into 4cm/1½in slices with a sharp knife. Arrange the slices in the tin, placing them cut-side up. They should fit fairly snuggly.
Cover the tin loosely with oiled cling film and leave in a warm place for about 45 minutes or until the dough is well risen.
Preheat the oven 180C/350F/Gas 4.
Bake the brioche for 30 minutes, then remove it from the oven and brush lightly but generously with the beaten egg yolk. Return the brioche to the oven for a further 10 minutes until golden brown.
Cool in the tin for 10 minutes, then release on to a wire rack.
Sprinkle with sugar and serve warm or cold.
