In a stand mixer with a dough hook, combine the flour, yeast, water, cream, eggs and sugar; knead until the dough is smooth.
While the mixer is running, add the salt and butter, 1 tablespoon at a time, kneading until the butter is incorporated each time. The dough will be sticky until the butter is fully incorporated.
Cover the bowl with plastic wrap and let the dough rise until it has doubled in size, about an hour in a warm room. Meanwhile, spray a 9x5 inch loaf pan with baking spray.
Turn the dough onto a lightly floured surface and pat it into a rough 8 inch square. Fold the top half to about the middle of the dough and press the edge down to secure it. Fold the top over again, this time to within about an inch or so of the bottom. Press the edge to seal. Now pull the bottom of the dough up to meet the dough roll you've created and seal the seam. Pinch the ends closed and place the dough, seam-side-down, in the prepared loaf pan. Cover the pan with plastic wrap; refrigerate overnight or up to 24 hours before baking. The dough should be fully risen after about 6 hours, but a longer rest is good for it.
DAY TWO (BAKING)
Take the pan out of the refrigerator and preheat the oven to 350 degrees F. Remove the plastic wrap and brush the top of the bread with egg wash.
Bake the bread until it is richly browned and the internal temperature reaches 190 degrees F. on an instant-read thermometer, about 50 minutes. Remove the bread from the pan and cool completely on a rack before slicing.
Notes
Because of the large amount of butter in this bread, it needs to be added at the end of kneading or it would be difficult for the gluten to form properly. Adding butter to dough when you're kneading by hand is messy. It can be done, but I highly recommend using a stand mixer to do the work for you.