Heat oven to 350 degrees F. Line a bakesheet with parchment paper.
Mix all ingredients, with exception of the macaroni and cheese until well blended. Place 2 tablespoons of mixture into the palm of your hand and then flatten it into a patty. Place a small amount of macaroni and cheese at the center. Fold patty around the macaroni and cheese, pinch and cover as needed to make sure the stuffing is completed covered. Place on parchment paper an inch apart, bake for 35 -40 minutes.
Spread marinara sauce inside of bread and fill with cooked meatballs and cheese. Place assembled sandwiches under broiler for 2-3 minutes or until cheese melts. Serve immediately.