Start by preparing the yeast with warm water and sugar in the mixer bowl, stir them all together and let the yeast do its magic for about 5 minutes. You'll notice it will get bubbly.
Add the eggs, and with the mixer on medium, beat for about a minute after which add the 2 teaspoons of salt.
With the mixer on low speed, add 2 cups of the flour and mix for 5 minutes. Add the 2 more cups of flour and mix for 5 more minutes. With the mixer still on low speed add the chunks of soft butter and mix until the butter is fully incorporated in the dough.
With the mixer still on low, add the remaining 1/2 cup of flour and continue mixing for a couple more minutes. If needed switch from the paddle attachment to the dough hook.
Place the dough into a well buttered bowl, cover with plastic wrap and refrigerate overnight.
The next day, let the dough sit out for about an hour before working with it. Butter 2 loaf pans well. Divide the dough in half and roll each half into a rectangle wide enough to fit your loaf pan. Roll it up and place the dough in the loaf pan, seam side down. Repeat with other half. Cover the pans with a damp towel and set aside to rise at room temperature until doubled in volume, 2 to 2-1/2 hours.
Preheat the oven to 375 F degrees.
When the loaves have risen, brush the top of each with the egg wash and bake for 40-45 minutes, or until the top springs back and it sounds slightly hollow when tapped. Turn the loaves out onto a wire rack to cool.