Baked French Onion Meatballs with Caramelized Onions - My Homemade Recipe

Ingredients

• 1 1/4 pounds ground chicken.
• 1 slice whole grain bread.
• 1 egg, beaten.
• 6 tablespoons salted butter.
• 3-4 medium yellow onions, sliced.
• 3/4 cup dry white wine.
• 3 cloves garlic, chopped.
• 2 cups mushrooms, sliced.
• 2 tablespoons fresh thyme.
• 2 tablespoons fresh sage.
• 2 1/2 cups chicken broth.
• 1/4 cup whole milk or cream.
• 6 slices French bread.
• 1 cup gruyere cheese.