Mozzarella Stuffed-Crust Onion Pie | Real California Milk

Ingredients

• 6 onions, thinly sliced
• 2 tbsp. Real California butter
• 1 tsp. concentrated beef stock
• 1 6-oz. can of tomato paste
• 6 tbsp. hot water
• 1 tbsp. dried oregano
• 1 tbsp. red wine vinegar
• 1/2 tsp. sugar
• 1/4 tsp. garlic powder
• 1/4 tsp. ground cayenne (optional)
• Salt and pepper
• All-purpose flour for the work surface
• 1 16- to 20-oz. pizza dough
• 1 lb. shredded Real California mozzarella cheese, divided
• 1 lb. sliced Real California provolone cheese
• 1/2 lb. shredded Real California Gruyere cheese
• 2 tbsp. chopped fresh parsley