Chop beef into bite sized pieces.
Place beef, onion, and green pepper in slow cooker.
Stir mushroom soup together with 2 cups broth.
Pour into slow cooker and add remaining broth.
Cook on high 5-6 hours or low 7-8 hours.
Slice bread and top with up to 1 cup of shredded Swiss cheese.
Broil in oven till toasted.
Serve bread with soup.
Top bowls of soup with extra Swiss, if desired.