In your mixing bowl add milk, yeast and sugar together and let proof about 10 mins until the yeast is dissolved.
Add the flour, salt and 2 Tbsp softened butter to the warm milk mixture. Mix with a dough hook until it's combined, then mix 2-3 more mix until it's smooth (if you don't have a bosch you can knead by hand about 5 mins)
Let the dough sit (covered) for 1 hour (or until doubled in size.
With your hands, on the counter (or in your Bosch) mix the cold butter and 3 Tbsp flour until it is smooth and without lumps. Work quickly to keep the butter cold.
Place the butter on plastic wrap and shape it into a 9x6 in rectangle. Wrap and refrigerate the butter 30 mins
knock the dough down, knead lightly in the bowl and refrigerate for 30-45 mins.
Roll out the dough onto a lightly floured surface to a 15 x 8 inch rectangle.
Take the rectangle of butter and place over 2/3 of the dough leaving a 1/2 inch border on 3 of the side and about 5 inches on the other. Fold over the excess 5 inches of dough then fold over the buttered side like you were folding a business letter. Seal the edges and rotate 1/4 turn.
Roll out the dough/butter into a 18x8 inch rectangle, fold into thirds again, wrap in plastic wrap and refrigerate 30 mins (first turn)
Repeat rolling out, folding, wrapping and refrigerating 2 more times (2nd and 3rd turns)
Roll out the dough one more time, roll into thirds again, wrap in plastic wrap and refrigerate, this time for an hour or overnight (4th turn) (at this point the dough can also be frozen, let thaw completely before proceeding.).
Roll out dough into a rectangle about 10 x 15 inches (it will be about 1/4 inch thick)
Cut down the center, creating two 5 x 15 inch rectangles
Mark the inside about every 3 3/4-4 inches (you'll get 5 marks)
Mark in the CENTER of those marks on the other side (so there will be 4 marks)
Cut from the mark on one side to the marks on the other side, you'll get about 14 triangles
Cut a half inch mark in the center of the fat end.
Tug a bit to pull the fat side apart and then stretch the point down (but be careful not to rip the layers)
Starting at the fat end roll up leaving the tip underneath and curling the end in.
Place on a baking sheet and cover with plastic wrap sprayed with non stick spray, like pam or bakers joy, and let rise until increased by almost half, 1 1/2-3 hours.
Brush each croissant lightly with the egg. Bake at 375 for 20-25 mins.