Preheat the broiler.
In a small sauté pan over low heat, melt the butter with the garlic. Continue to cook over low heat until the garlic begins to soften, about 2-3 minutes. Add parsley and cook another minute. Remove from heat and spread onto the inside of each side of the bread. Place under the broiler and toast until golden brown. Let cool.
Spread mayonnaise onto bread. Layer turkey, ham, salami and provolone onto bottom half of bread. Sprinkle with salt and pepper. Top with lettuce, peppers, and onion. Wrap tightly in aluminum foil and place a heavy-duty skillet (I use an iron skillet) on top. Let sit 30 minutes. Slice and serve.