Let’s start with the green mixture: blend the basil (washed and dried) with the oil and half the milk.
Dissolve the yeast in the remaining milk, just warmed up.
Place the flour, salt and sugar in a well in a bowl, pour the egg yolk, yeast and basil cream into the center and knead until you obtain a smooth mixture.
Cover the bowl with cling film and leave to rest in the oven with the light on for about 2 hours or until it has doubled in volume.

In the meantime, let’s move on to the red dough: dissolve the yeast in half the milk, just lukewarm; dissolve the tomato paste with the remaining milk, then also incorporate the egg yolk and oil.
Pour flour, salt and sugar into a bowl, pour yeast and red mixture into the center and work until you obtain a homogeneous dough.
Cover with cling film and let this rest in the oven too.

Meanwhile, let’s prepare the white dough: dissolve the yeast in the milk, always lukewarm.
Place flour, salt and sugar in a bowl, mix and incorporate egg yolk and milk, then cover with cling film and leave to rest.

When the 3 doughs have at least doubled in volume, prepare the other ingredients, cutting both cheese and ham into cubes.

Take one dough at a time, deflate it with your hands and divide it into 10 equal pieces.

Press each piece with your hands, fill with a few cubes of cheese and ham and close the dough over the filling to create a ball.

Once you have obtained your 30 balls of 3 different colours, place them in the mold lined with baking paper and lightly greased, trying to alternate the colors between them, then let them rise for at least 30 minutes, always in the oven with the light on and off.

Finally brush with the lightly beaten egg white and cook for about 30 minutes or until golden in a preheated fan oven at 170°C.

The tricolor Danube is ready, all you have to do is let it cool before turning it out and serving it.