Prepare the meatballs and cashew mozzarella according to recipe instructions.
Pre-heat your broiler. Line a baking sheet with parchment.
Place the tempeh meatballs into a saucepan with the marinara sauce. Bring to a simmer. Simmer the meatballs for five minutes, then remove them from heat.
Split the Italian rolls in half. Add 4-5 marinara-coated meatballs to the inside of each roll. Top with about 1/4-1/3 cup of the melty cheese sauce. Broil for 3-5 minutes, or until the bread is browning and crusty at the edges. Serve.