Combine warm milk together with yeast and two cups of flour. Combine by whisking all the ingredients together. Cover the bowl with a towel and set it aside in a warm place for about 30 minutes.
While the dough is rising, separate the egg yolks from egg whites. Whisk egg yolks together with 1 cup of sugar. In a separate bowl, whisk whites until they turn into a foamy (stiff peeks) mixture.
Mix egg yolks into the dough, followed by butter, vanilla extract and egg whites.
If you're using your mixer, mix in the rest of the flour in small portions. Knead the dough until it becomes elastic. In the picture, you can see how smooth the dough will turn out. The dough is going to be more on a sticky side.
Cover the dough with a towel and set it aside to rise for about an hour.
While the dough is rising, soak raisins in warm water for 15 minutes. Drain the raisins completely and mix them into the dough; Cover with a towel and set it aside, once again.
The dough will be sticky, so you may want to oil your hands. Fill up each buttered pan, half way, with the dough. Cover the bread with a towel and set aside to rise for about 30 minutes.
Bake at 350°F for about 30 minutes, depending on the size of your paska. Let the bread cool completely to room temperature.