Prepare the slices of bread.
Slice the tomato and onion thinly.
Cook the bacon in a pan and place it on the bread.
Spread mozzarella cheese and pizza sauce on the bread.
Add the sliced tomato, onion, and bell pepper.
Sprinkle additional cheese and cover with another slice of bread.
Add butter to a pan and grill the sandwich on both sides until golden brown.
Cut into bite-sized pieces to finish.