French onion meatball sub

Instructions

1. Make the garlic butter. In a small bowl, combine the softened butter, grated garlic, parsley, and a pinch of kosher salt. Mix until smooth and set aside.
2. In a large bowl, combine the ground beef, breadcrumbs, grated Gruyère, parsley, eggs, salt, and pepper. Mix just until combined, then roll into 16 evenly sized meatballs.
3. Heat a large cast-iron skillet over medium-high heat. Sear the meatballs until deeply browned on all sides, about 6–8 minutes. They do not need to be fully cooked. Remove from the skillet and set aside.
4. Reduce the heat to medium and add the oil to the same skillet. Add the sliced onions and cook, stirring occasionally, for 30–40 minutes until deeply caramelized.
5. Stir in the Worcestershire sauce, thyme, and several cracks of black pepper. Cook for 1 minute.
6. Add the demi-glace and beef stock, scraping up all the browned bits from the bottom of the pan. Bring to a gentle simmer.
7. Return the meatballs to the skillet, nestling them into the onions. Top evenly with the shredded Gruyère and transfer to a 400°F oven for 10–15 minutes, or until the meatballs reach 160°F and the cheese is melted and bubbling.
8. Slice the baguettes in half and generously spread the cut sides with the garlic butter. Toast until golden brown and crisp around the edges.
9. Place four meatballs into each baguette. Spoon over plenty of the caramelized onions, melted Gruyère, and a generous amount of the French onion jus. Serve immediately while hot.