Prepare saffron essence:  Crumble saffron threads in a small bowl, add 3 tbsp. hot water, steep 30 minutes or longer, strain and press out essence.  Reserve.
Remove zest from orange and lemon.  Set aside.
Plump raisins (if adding):  Pour boiling water over raisins.  Let stand 5 minutes, drain. Set aside to dry.
​

Grease pans:  Use three springform pans (10 x 3 and 9 x 3 and 8 x 3) or 4 small to medium-sized stainless steel pots that are oven-proof.  Corning ware may also be used, but bottoms tend to burn.  I have concerns about using metal coffee tins because of its metal content.  It’s hard to know what they are made of these days.
*TIP:   Need warm place to rise dough?  Warm your oven at the lowest setting, then immediately turn oven off.  Cover dough with a moistened dish towel and place in oven to rise.  Placing a small bowl of hot water in oven also helps.  Leave oven door slightly ajar.

Prepare sponge:  Pour milk into a large bowl.  Stir in 4 cups flour and beat until smooth.  Add prepared yeast and stir until well blended.  Cover with moistened dish towel.  Set aside to rise in a *warm place about 1 ¼ hours - until sponge has doubled in size.

When the sponge is almost ready, in a medium bowl, beat eggs well.  Whisk in sugar, butter, salt, orange and lemon zest and saffron until blended.  

Stir egg mixture into sponge (large bowl).  Add 2 cups flour to egg/sponge mixture, one cup at a time, and stir until blended. Gradually add another 6 cups flour.  Add more flour if needed.  Dough should be slightly sticky.  Flour your hands and knead until the dough is smooth and no longer sticks to your fingers. 

Remove dough to a lightly floured board and knead 10 minutes.   Oil the large bowl.  Roll the dough in the bowl until it is covered in oil.  Cover with a damp dish towel and set aside to rise until double in bulk, about 1 ½ hours.  Punch down (knead in raisins now).