In a large mixing bowl, or in the bowl of an electric mixer, combine yeast and milk, stirring to mix. Let sit 10 minutes until foamy.
Add flours, oats, butter, brown sugar or honey, and salt and mix on medium-low speed until a "shaggy" dough forms.
Increase speed of mixer to medium and knead for 5-6 minutes, until well formed, smooth ball forms. If dough is still pretty sticky, add a couple more tablespoons of flour until it is smooth.
Place dough in a lightly greased bowl, cover and allow it to rest for 1 hour; it'll become quite puffy, though it may not double in bulk.
Remove dough and form into a log, then place into a well-greased 9x5" loaf pan. Let rise for 90 minutes.
Preheat oven to 350 degrees F.
Bake in preheated oven 35-40 minutes, until golden on top.
Let cool.
Slice and enjoy!