In a bowl, mix all ingredients at the same time (except butter, one egg and the filling) by hand or in a blender (5 minutes at slow speed, 4 minutes at 2nd speed) until you reach a ball of smooth and homogeneous dough.
Add the butter towards the end of the kneading (step 2).
Rest the dough at room temperature, sheltered from the air, for 1h45.
Cut the dough into 18 dough pieces (about 100 g each).
Shape dough pieces and place them on a baking sheet covered with parchment paper.
For gilding, in another bowl, beat the last egg and brush the dough pieces.
Reserve the dough and let it ferment in the air for about 60 minutes.
Preheat the oven to 350 ° F (180 ° C).
Cook the dough for 12 to 15 minutes.
Take out of the oven and wait until the bread is at room temperature before slicing it in half.
