Cook the Meatballs:

1. In a large skillet over medium heat, heat olive oil.
2. Cook meatballs until seared on all sides, about 4 minutes.
3. Add marinara sauce, gently stir, and cover with a lid.
4. Reduce heat and simmer until meatballs are no longer pink, about 8-10 minutes more. The internal temperature should reach 160°F.

Prepare the Bread Boats:

1. Cut a long rectangle through the top of each sandwich roll and hollow out the center to make a boat.
2. Lay three slices of provolone cheese over each roll to cover the hollowed-out area.
3. Bake for 5 minutes, until the cheese is melted.

Assemble and Bake:

1. Place four meatballs on top of the melted provolone cheese in each roll.
2. Spoon marinara sauce over the meatballs.
3. Sprinkle shredded mozzarella and Parmesan cheeses evenly over the meatballs.
4. Bake in the oven for 6-8 minutes more. Broil if desired for a crispier top.

Enjoy these savory meatball boats as a hearty, flavorful, and simple-to-prepare meal for your family! Perfect for a quick and easy dinner on busy weeknights.