Start adding the flour half a cup at a time and mix well. The dough is ready when it no longer sticks to your hands. Add additional flour if you need it.
Melt the butter in a sauce pan or in the microwave. In a mixer add the melted butter and sugar and mix until the sugar and butter are well incorporated. Add the eggs and continue mixing until the mixture is light. Add the yeast mixture, remaining milk, salt and continue mixing until everything is well incorporated.
Add ¼ cup of the milk to a cup and warm it up in the microwave until it's lukewarm. Add the yeast to the milk, a tsp of sugar and mix well. Let the yeast mixture sit for about 10 min until it froths up and bubbles.