Pour boiling water over 1 cup rolled oats in a heatproof bowl, stir, cover loosely and stand 20 minutes until thick and spoonable.
Stir in 1/4 cup milk and honey. Wait until the oat mixture measures 85°F to 105°F and is below 110°F.
Add yeast, salt and bread flour. Mix on low 2 minutes until no dry flour remains, then cover and rest 10 minutes.
Knead 3 minutes, add softened butter in pieces, then knead 5 to 7 minutes until elastic and slightly tacky. Add flour only 1 tablespoon at a time if still paste-like.
Place in a lightly greased bowl, cover and rise until roughly doubled and visibly puffy, about 60 to 90 minutes.
Press into an 8-by-10-inch rectangle, roll tightly from a short side, seal the seam and place seam-side down in a greased 8 1/2-by-4 1/2-inch pan.
Cover and proof until the center crowns about 1 inch above the pan rim, commonly 45 to 75 minutes. Heat the oven to 350°F.
Brush the risen loaf gently with 1 tablespoon milk and sprinkle with 2 tablespoons rolled oats.
Bake 35 to 42 minutes, until golden and the center reaches 190°F to 195°F. Tent loosely if browning early.
Turn out of the pan within 5 minutes and cool upright on a rack for at least 2 hours before slicing.
