Step 1: In a small bowl, combine warm milk, sugar, and yeast. Stir gently and let it sit for 5-10 minutes until the mixture becomes foamy and bubbly.
Step 2: In a large mixing bowl or the bowl of a stand mixer, whisk together the bread flour and salt. Create a well in the center.
Step 3: Pour the yeast mixture and the beaten egg into the well. Using a dough hook or a wooden spoon, mix until a shaggy dough begins to form.
Step 4: Gradually add the softened butter, one tablespoon at a time, while kneading. Continue to knead for 8-10 minutes (by mixer) or 15 minutes (by hand) until the dough is smooth, elastic, and passes the windowpane test.
Step 5: Lightly grease a bowl and place the dough inside. Cover with a damp cloth and let rise in a warm, draft-free spot for 1 to 1.5 hours, or until doubled in size.
Step 6: Gently punch down the dough to release excess air. Turn it out onto a lightly floured surface and shape into a rectangle roughly the width of your loaf pan.
Step 7: Roll the dough tightly into a log and place it into a greased 9×5 inch loaf pan. Cover and let rise for another 45-60 minutes until the dough has risen about an inch above the rim of the pan.
Step 8: Preheat your oven to 350°F (175°C). Brush the top of the loaf with a simple egg wash (1 egg beaten with 1 tbsp milk).
Step 9: Bake for 25-30 minutes, or until the top is golden brown and the internal temperature reaches 190°F. Remove from the pan and cool on a wire rack before slicing.