French Onion Meatballs

Ingredients

• 1 1/2 c. fresh breadcrumbs or panko breadcrumbs
• 1/4 c. plus 2 T. whole milk
• 1 1/2 lb. ground beef (85/15)
• 1 T. chopped parsley
• 1 t. fresh thyme leaves, plus more for garnish
• 1 t. Herbes de Provence
• 1 t. salt
• 1/4 t. black pepper
• 1/2 large, white onion, finely minced
• 4 cloves garlic, pressed through garlic press
• 3/4 c. grated Gruyere cheese, divided
• 1 egg, whisked
• 1 c. shredded, whole milk Mozzarella cheese
• 4 T. olive oil, divided use
• 2 T. butter
• 2 1/2 large, white onions, halved and sliced
• salt
• black pepper
• 1 t. dried thyme
• 1/4 c. sherry or white wine
• 1 1/2 T. flour
• 2 1/4 c. beef stock
• 2 t. fresh thyme leaves