Easy & Healthy Cabbage Rolls Casserole Recipe

1 tbsp olive oil
1 large onion, diced
6 cloves garlic, crushed & divided
1.5 lbs extra lean ground turkey
2 cans (28 oz each) crushed tomatoes or tomato sauce, divided
1 cup brown rice, uncooked
1 cup water
2 tsp brown sugar, divided
5 bay leaves
1/2 tsp salt
1/4 tsp ground black pepper
1 medium cabbage (3 lbs), thinly shredded
1/4 cup parsley, finely chopped (for garnish)
Greek yoghurt (for garnish)
8 slices fresh mozzarella cheese (optional)