Next morning, with a mixer or by hand, mix 800 g of flour with 480 g of milk until to a shaggy dough. Cover and let it rest for 30 minutes. Disolve yeast with 20-30g milk and leave aside.
Then add the remaining products, biga and yeast and knead until you get a smooth and elastic dough. This takes about 10 minutes.
Put the dough in a bowl, cover with a towel and leave to rise at room temperature (about 24-26C). It takes about 60 minutes, but you are not guided by time, but by volume.
Once the dough has doubled in volume, place it on a lightly floured surface and form two tight balls. Cover and let them rest for 15-20 minutes.
Then roll with a rolling pin in a circle about 5-6 mm thick. Cut a cross first and then once more into eight triangles. Roll each triangle starting from the wide side, lightly pressing the edges and finally twisting them slightly inwards. Place in a greased pan or place baking paper on the bottom. Cover with a towel and leave at room temperature for the final leavening, but not more than 26C, so that the butter does not melt in the dough. Wait until they double in volume.
Preheat the oven to 170C, spread the rolls with beaten egg with a little water and sprinkle with poppy seeds on top. Bake until done.