Creamy Ricotta Beef Stuffed Shells Pasta

Ingredients:
20 large pasta shells
1 lb lean ground beef
1 cup ricotta cheese
1 ½ cups shredded mozzarella cheese, divided
½ cup grated Pecorino Romano cheese
1 large egg, beaten
2 ½ cups tomato basil sauce
1 tsp dried oregano
2 cloves garlic, minced
Salt and black pepper, to taste
Fresh parsley, chopped (for garnish)

Instructions:
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