Dissolve yeast in warm water. Let sit 5 minutes.
Combine sugar, salt, 1 cup of flour in a large mixing bowl. Stir.
Add milk, melted butter, and water/yeast mixture. Stir.Add remaining flour and stir until sticky dough forms. Dump the dough out onto a floured surface. Sprinkle with flour and knead a few times so that it is easier to work with.
Roll dough out into a long 1/2" thick rectangle. Fold the dough into thirds (like a letter) place onto a baking sheet. Cover with plastic wrap and chill for 1 hour. Note: you can just place the dough onto the baking sheet without folding it. I just find it easier to work with if it is folded. Place the two sticks of butter in between two pieces of parchment or wax paper.
Pound with a rolling pin until the butter is about 1/2" thick (6" x 8" rectangle).
Fold parchment or wax paper around butter and let butter chill in the refrigerator until the dough is ready (1 hour).
Flour your work surface and roll chilled dough into a 10" x 16" rectangle (no need to unfold the dough first, just roll it out).Place chilled butter in the center of the rectangle. Fold dough around the butter, folding the bottom and top over then the sides. Press seams together to seal.
Flip the dough over to the other side, sprinkle with flour, and pound with a rolling pin to make it easier to roll. Roll dough into a 10 x 20" rectangle.
Fold the dough into thirds, like a letter.
Wrap with plastic wrap and write a "1" on the plastic wrap with a marker. This means that you have pressed and folded the butter 1 time.Let dough chill in the refrigerator for 45 minutes. Remove the plastic from the dough, and with the folded edges on the sides and the open edges towards you, pound with a rolling pin to flatten slightly then roll into a 10"x 20" rectangle (again). Fold into thirds, like a letter.
Wrap with plastic wrap and write a "2" on the plastic wrap with a marker. This means that you have pressed and folded the butter into the dough 2 times. Let dough chill in the refrigerator for 45 minutes. Repeat this process until you have pressed and folded the butter 4 times.After the 4th time, allow the dough to chill for AT LEAST 4 hours. You can leave the dough overnight and finish up the croissants the next day if you'd like. When the dough is ready, roll out into a 9" x 18" rectangle. Cut into 8 squares using a pizza cutter.
Cut each square in half, diagonally to form 16 triangles.
Flatten each triangle, then roll (beginning at the wide end) into a croissant shape.
Pinch the end of the triangle and press against the bottom of the croissant to seal.
Place croissants onto a lightly greased baking sheet.Allow to rest in a warm place for 90 minutes or until crossants have doubled in size. Mix egg and water together then brush over croissants.
Bake croissants at 425 degrees for 15-18 minutes or until golden brown.