Preheat the oven to 350 degrees, and grease a loaf pan well.
Place all of the ingredients for the bread into a mixing bowl, and blend until smooth. Allow to rest for 10 minutes.
Spread the mixture into the loaf pan, and bake for 60 minutes, or until cooked through.
Allow the bread to cool.
Slice the bread.
Spread some butter on one side of each slice of bread.
Place a slice of bread butter side down on a plate.
Top the bread with a slice of provolone, mozzarella and American cheeses.
Sprinkle on some Italian seasoning and garlic powder.
Place another piece of bread on top, with the butter side facing out.
Heat a skillet over medium heat on the stove.
Add the sandwiches, butter side down into the heated skillet.
Toast the sandwiches evenly on both sides until crispy, and the cheese has melted.