Meatball Sub

Name: Meatball Sub
Ingredients: 1/3 cup whole milk , warmed; 1 slice white bread , crumbled; 1 pound ground beef (80 to 85% lean); 1/4 cup freshly grated Parmesan cheese; 1 large egg; 1/2 tablespoon fresh chopped parsley; 1 teaspoon kosher salt; 1/2 teaspoon dried oregano; 1 cup Italian breadcrumbs , for coating; 1/3 cup olive oil , for searing; 24 ounces good quality marinara sauce; 4 large hoagie rolls , 6 to 8 inches long; 1 tablespoon butter or olive oil; 8 slices provolone cheese; Fresh basil , for garnish; Banana peppers , for garnish (optional)