Combine the Tangzhong ingredients in a sauce pan and cook over medium low heat until a thick paste forms. The consistency is like soft mash potatoes. Cover and let it cool to room temperature ~20 minutes.
15 minutes after making the Tanzhong, combine milk and old fashion oats in a pot and bring to a simmer. As soon as it simmers, turn off the heat and let the mixture cool for about 5 minutes. Add in honey and test the temperature. It should be warm but not too hot to the touch. Mix in yeast and let sit for another 5 minutes.
Add oil and salt to the yeast mixture and slowly add in flour mix. Knead the dough until smooth and place it in a lightly greased bowl. Let rise for about 1 hour.
Turn risen dough onto a floured counter and roll out into a square slightly wider than your loaf pan. Fold the long sides into each other to create even edges and press to flatten. The dough should now be slightly smaller than the loaf pan. Take the bottom side and tightly roll up the dough. Pinch the edges to seal and place the dough onto a parchment lined loaf pan seam side down and cover with a wet towel. Let rise for about an hour.
Preheat oven to 350º F. Optional: brush the top of the loaf with egg wash or milk and sprinkle oats on top. Bake for 45 minutes or until golden.
Let cool for about 20 minutes before slicing.