Italian Stuffed Peppers

Name: Italian Stuffed Peppers
Prep time: 20 min
Cook time: 55 min
Total time: 1 h 15 min
Cuisine: Italian
Ingredients: 6 large bell peppers (cut in half and seeds removed); 1/4 cup olive oil (divided); 1 1/2 pounds ground chuck; 2 cups cooked white rice; 8 cloves garlic (minced); 1 cup low sodium beef stock; 1 cup Pecorino Romano (grated); 1/4 cup parsley (minced); 1/4 cup basil (chopped); 1/4 teaspoon crushed hot red pepper flakes; 2 teaspoons dried oregano; 4 cups marinara sauce (divided, see notes below); 3/4 cup water; 1 cup mozzarella (grated); 2 1/2 teaspoons kosher salt (divided, plus more to taste)