Mix the yeast with a teaspoon of sugar and salt to the luke warm milk, keep aside until the yeast turns foamy. Meanwhile take the flour,egg yolks,sugar in a large bowl, add gradually the foamy yeast and turn everything as a soft dough.
Now add the butter and knead everything for 10 minutes.
Divide the dough into equal balls, add nutella to one dough ball and knead well to get a chocolate brioche dough.
Arrange these doughs into two bowls covered with a towel, keep it aside for atleast for 2 hours until they double their volume. Knead the dough again for a few minutes.
Make small balls of the dough out of this both doughs, take a usual dough ball and roll it as small disc, drop the chocolate dough ball and wrap it or vice versa.
Roll it as oval shaped dough, fold it as two, and make a slit with a knife, keep the edges intact. Turn the dough and sharp the edge to make a heart shaped brioche. Continue the same process with the remaining dough.
Arrange the brioche dough over a baking paper lined over a baking tray and keep it aside for half an hour.
Preheat the oven to 176 degrees celsius, brush the brioche with milk generously. Bake for 20-25 minutes until the crust turns brown.
Let it cool completely. Enjoy this brioche with your favourite spread.