In the mixer bowl, fitted with the paddle attachment, mix the flour, sugar, and vanilla sugar.
Add the butter, cut into small cubes, and mix until a crumbly texture is obtained.
Add the egg and mix until the dough forms a ball.

Roll out the dough into a rectangle, about 1/4″ (0.5 cm) thick.

Preheat the oven to 375 F (190 C).

In a bowl, mix the almond powder, sugar, almond extract, egg white, and enough rose water to form a pliable dough.

Spread the almond dough with a spatula over the shortbread dough, then roll into a log, making sure to put the seam underneath.

Brush with the remaining egg yolk, make a few knife cuts, and dust with turbinado sugar.
Bake for 45 minutes. Remove from the oven and let cool before cutting into slices and enjoying.