Step 1

Combine the flour, yeast, sugar and salt in the bowl of a stand mixer fitted with a dough hook and mix on low speed to combine. Add the milk and 6 eggs and mix on low until well combined. Increase the speed to medium-high and mix until the dough starts to pull away from the sides, about 5 minutes.

Step 2

Reduce the speed to medium and start adding the butter, a little at a time and waiting until it is completely incorporated to add more, about 5 minutes. Return the mixer to medium-high and continue to mix until the dough is glossy and slightly tacky but not sticky, about 7 minutes. Transfer to a large bowl, then cover with plastic and refrigerate 8 hours and up to overnight.

Step 3

Generously butter two 9-by-5-inch nonstick loaf pans and divide the dough between them. Generously butter two pieces of plastic wrap large enough to cover the pans and place them butter-side down loosely over the pans. Let the dough rise until it comes to 1 inch above the rims of the pans, about 3 hours.

Step 4

Preheat the oven to 350 degrees F.

Step 5

Beat the remaining egg with 1 tablespoon water. Remove the plastic wrap and brush the top of each loaf with the egg wash, then place the pans on the middle rack of the oven. Bake, rotating halfway through, until golden brown and the internal temperature of each loaf is 190 degrees F, about 30 minutes. Remove the pans to a wire rack and let cool 5 minutes. Run a knife around the sides of the loaves to loosen and remove the loaves from the pan. Let cool completely on the rack.