Pour the milk into a small saucepan and bring it to a warm temperature. Add the butter while the milk is heating up. Once the butter has melted and the milk is warm to the touch (not hot), remove from the heat and add the yeast. Stir in the yeast until combine, then set aside for 10 minutes until the milk/yeast mixture begins to froth.
While waiting for the yeast to activate in the milk mixture, in a mixing bowl, combine the flour, granulated sugar, and salt. Create a well in the middle of the dry ingredients. To the well, add the yeast mixture, the egg yolks, and vanilla. Mix all ingredients until they are combined.
Knead for about 10 minutes until the dough is soft and smooth. If the dough is too dry, add a bit more warm milk and knead until smooth.
Find a large mixing bowl and butter the entire interior of the bowl to make sure the dough won't stick once it rises. Place the dough into the bowl, cover and set in a warm place (@80 degrees Fahrenheit) until it doubles in size (about 1-2 hours).
Punch down the dough after the first rise, then roll into a ball, dividing into four equal quadrants (these will be the four layers).
On a floured surface, roll out one at a time each of the four pieces of dough into round 12" in diameter thin layers. I use a dinner plate, set it on top of the rolled-out dough, and, with a paring knife, cut around the edge of the plate, removing the excess dough.