Pizzadilla (Grilled Pizza Sandwich)

Ingredients (7)

• + 20 ounces prepared pizza dough add to pantry
• + 2 tablespoons olive oil, divided, or as needed add to pantry
• + 1 cup pizza sauce, divided add to pantry
• ✓ 8 ounces mozzarella cheese, divided
• + ½ cup cooked Italian sausage, or to taste add to pantry
• + ½ cup cooked mushrooms, or to taste add to pantry
• + ½ cup cooked red onions, or to taste add to pantry