In a small bowl or bowl of a stand mixer, dissolve the yeast and a pinch of the sugar in the warm water. Let stand until foamy, about 5 to 10 minutes.
To mix the dough by hand, In a large bowl, combine the remaining sugar, the salt, melted butter, milk, the yeast mixture and 1/2 cup of the flour, and mix with a wooden spoon until blended. Gradually add the remaining flour 1/2 cup at a time and mix just until the dough comes together in a sticky ball.
To mix the dough by stand mixer, In the large bowl of a stand mixer fitted with the paddle attachment, combine the remaining sugar, the salt, melted butter, milk and the yeast mixture and mix on medium speed until combined. Gradually add the flour 1/2 cup at a time and mix just until the dough comes together in a stick ball.
On a lightly floured surface, roll out the dough into a rectangle about 1/2 inch thick. Transfer to a large baking sheet and cover with plastic wrap. Place in the fridge until chilled, about 40 minutes.
While the dough is chilling make the butter package. I found it was easiest to place all four sticks of butter together in a gallon size ziplock bag. Then using a rolling pin, beat the butter on a work surface to flatten it. Continue to gently beat the butter with the rolling pin to shape the butter into a 6-by-8-inch rectangle. This part was really kind of hard, but just keep working it. Once the butter is in the shape of a rectangle place it back in the fridge to stiffen up again. Don't worry if your butter is not in a perfect rectangle. It's still going to work.
Now it is time to laminate the dough, which just means fold the dough with the butter to create layers. On a lightly floured work surface, roll out the dough into a 16-by-10-inch rectangle. With a short side facing you, place the butter in the middle of the dough. Fold the ends up like a letter. Fold over the upper half to cover the butter and press the edges together to seal. Then fold over the remaining lower half and press the edges together to seal. Turn dough again so the short side is facing you, and use the rolling pin to press down equally on the dough to help flatten it. Roll dough into a 15 x 10 inch rectangle. Then fold the dough like a letter again, with a short side facing you, fold the bottom third up, then fold the top third down. Use your hands to pull the dough into a rectangle shape. You should now have a roughly 11 x 6 inch rectangle. This completes the first turn. Wrap in plastic wrap and place in the fridge to chill for 45 minutes.
Return the chilled dough to the lightly floured work surface with a folded side to your left and repeat the process to make 3 more turns, rolling, folding and chilling the dough each time, for a total of 4 turns. After the final turn, refrigerate the dough for at least 4 hours or overnight (I chilled mine overnight).
To form the croissants, cut the dough in half and place one half in the fridge while working with the other half. Roll out one half of the pastry on a lightly floured work surface into a 9-by-18-inch rectangle. Using a pizza cutter or sharp knife cut the dough in half lengthwise, and then cut the dough into triangles. Cut a small vertical slit right into the middle of the straight end, and using both hands, roll croissant up pushing the sides out to either side. Place on a baking sheet about 2-3 inches apart, cover with a towel and set in a warm place to rise for 1-2 hours. The croissants will not double in size like other yeast doughs do. After one hour position a rack in the middle of the oven and preheat to 425 degrees F.
Lightly brush the tops of the pastries with the egg mixture. Bake the pastries, 1 sheet at a time, until golden brown, 15-18 minutes. Transfer to a wire rack and let cool on the pan. Serve warm or at room temperature. Store in an airtight container at room temperature for up to 1 day. Makes 25-32 croissants.
To freeze the croissants before baking, complete the steps through step 8. Once all the croissants have been rolled place them on a baking sheet lined with wax or parchment paper. Cover the baking sheets and freeze for about 2 hours. Remove the pans and place the croissants in a freezer safe bag and seal. Immediately place back in the freezer and freeze for up to 6 months. To bake, allow the croissants to thaw overnight in the fridge and then bake as directed.
Optional fillings for the croissants: 1-2 teaspoons of pure pumpkin 1 -2 teaspoons peanut butter + 1 square of chocolate 1 teaspoon cinnamon sugar 1-2 teaspoons NutellaRoll each triangle up as directed. Brush each top with egg wash and for the pumpkin and cinnamon sugar croissants, sprinkle with more cinnamon sugar. Bake as directed.