Heat milk until luke warm in short bursts in the microwave. Combine milk, yeast, salt, sugar, and oil in your mixer with the dough hook attached. Mix until the yeast is evenly distributed into the milk mixture.
Mix together the buttermilk powder and flour. Start adding this to the milk while the mixer is running, and keep adding until dough has formed and is cleaning the sides of your mixer. (See notes for hand-kneading advice.)
Knead on medium or high speed in your mixer for 5-10 additional minutes after the flour is incorporated. The dough should be soft, and very stretchy, and lose a lot of the stickiness.
Put into an oiled bowl and cover with a towel. Let rise in a warm, draft-free place until doubled, about 1-2 hours. For best flavor, let rise in the fridge overnight.
Punch down the dough, and form into individual rolls. Smooth the tops by folding the bottom onto itself and pinching to seal. Place onto a large baking sheet that's been lightly sprayed with cooking spray or lined with parchment paper. Let rise until doubled, about 1-2 hours (depending on if you let rise in the fridge overnight or not!)
Bake at 350 until golden brown. Baking time will vary depending on roll spacing, how many pans you are baking at a time, and specific ovens. Watch carefully!
Rub tops of rolls with butter when they come out of the oven.
Notes
If you are kneading by hand, the dough will be slightly sticky. Keep adding small amounts of flour and knead until you can't knead anymore. For real - like 30 minutes. The dough should be soft and stretchy.