Dissolve the yeast in a small bowl with the sugar and a little water. Leave it to bubble.
Mix the flour with the salt, water and yeast into a smooth dough. Leave it in an oiled oven dish to rise for about 2 hours until doubled in volume.
Cut the olives into round slices.
Divide the risen dough into 2 balls and knead each one with olives.
Arrange them in 2 oiled and floured rectangular forms.
Smear them on top with the beaten egg yolk and bake for 30 min. at 392°F (200 °C).