Place the milk, water, butter, salt, sugar, onion powder, diced sauteed onion, oats, flour and yeast into the pan of a bread machine in the order recommended by the manufacturer. Select the Dough cycle, and press Start.
When the cycle has completed, remove the dough from the machine & cut into 8 equal pieces, and form into balls or oblong hoagies. Place on a baking sheet, and cover loosely with a towel. Set in a draft-free place to rise until doubled in size, about 60 minutes.
Preheat the oven to 325 degrees F (175 degrees C). Whisk together the egg white and water in a cup. Brush over the tops of the risen rolls, and sprinkle with remaining sliced sauteed onion.
Bake for 15 to 20 minutes in the preheated oven, until golden brown. Cool completely, then slice in half horizontally before using.
For the beef:
Place roast in slow cooker. Combine the Italian Spice Blend & beef broth; pour over roast & add in the pepperonicis.. Cover and cook on low for 8 hours or until meat is tender. Remove meat; shred with a fork and return to slow cooker.
Pile on sliced Onion Rolls & top with sliced white cheese, sauteed onions, and pepperoncini from the slowcooker if you wish.