In the bowl of a stand mixer, combine the milk, yeast, honey, 4 eggs, flour, and salt. Using the dough hook, mix until the flour is completely incorporated, about 4-5 minutes. Add 4 tablespoons room temp butter and mix until combined, about 2-3 minutes more.Cover the bowl with plastic wrap and let sit at room temperature for 1 hour or until doubled in size. Punch the dough down and roll out onto a lightly floured surface, creating a large rectangle that’s about 12x18 inches. Lay the thin slices of cold butter on one half of the dough, pressing gently to adhere. Fold the other half of the dough over butter, covering it completely. Roll the dough out into a large rectangle, roughly 12x18 inches. Fold 1/3 of the dough into the center, then fold the other 1/3 over the top of the first layer so you have three dough layers (like an envelope). Wrap the dough in plastic wrap and transfer to the freezer for 15-20 minutes until chilled. Alternately, you can chill the dough in the fridge for 1 hour or overnight. Meanwhile, butter two (9x5 inch) bread pans. Remove the dough from the freezer. Roll the (envelope shaped) dough into a rectangle (about 12x18 inches). Starting with the edge of dough closest to you, roll the dough into a log, keeping it tight as you go. When you reach the edge, pinch along the edges to seal.Cut the dough in half and place seam side down in prepared pans. Cover and let rise 45 minutes to 1 hour. Preheat the oven to 350 degrees F. Place the bread pans on a rimmed baking sheet and brush with the beaten egg. Transfer to the oven and bake 30-35 minutes or until dark brown on top. Let cool in the pans for 5 minutes, then flip out onto a cooling rack. Slice and serve warm or cold.