In a medium bowl, mix the ground beef, bread crumbs, parsley, egg, salt, and pepper.
3. Step
Pinch off a ball of the mixture, roll between your hands to make ping-pong ball-sized meatballs.
4. Step
Cook the meatballs over medium heat, turning to brown each side. Remove from heat and drain on a paper towel.
5. Step
Slice the baguette into thirds or fourths (each baguette piece should be roughly the same length of two meatballs).
6. Step
Hollow out the insides of the baguette pieces with a knife.
7. Step
Lay two slices of mozzarella on top of each other with a 1-inch (2 cm) overlap. Place two meatballs on the overlapping region, then fold the mozzarella tightly around the meatballs.
8. Step
Push the rolled meatballs and cheese into a baguette piece.
9. Step
Slice the stuffed baguette pieces into 1-inch (2 cm) slices, then place them tightly side-by-side on a baking sheet lined with foil.
10. Step
In a small bowl, mix together ingredients for garlic butter.
11. Step
Brush the garlic butter evenly over the baguette slices, making sure some drips in between the slices.
12. Step
Wrap the foil over the re-assembled baguette and bake for 15–20 minutes, until cheese is melted and the top is starting to brown.
