01 - Preheat oven to 375°F. Position the rack in the center of the oven.
02 - Unroll the pie crust and gently press it into a 9-inch pie dish. Trim any overhanging dough and flute the edges decoratively. Prick the bottom several times with a fork to prevent bubbling. Set aside.
03 - Heat olive oil in a large skillet over medium heat. Add the ground beef and cook, breaking it apart with a wooden spoon, until evenly browned and no pink remains, approximately 5 to 7 minutes. Drain excess fat if needed.
04 - Add the diced onion and minced garlic to the skillet. Sauté until the onion is softened and translucent, about 3 minutes. Pour in the marinara sauce, dried oregano, salt, and pepper. Stir to combine and let the sauce simmer gently for 5 minutes to meld the flavors. Remove from heat.
05 - In a medium mixing bowl, combine the ricotta cheese, egg, 1 cup of the mozzarella, Parmesan, chopped basil, and red pepper flakes. Stir until the mixture is creamy, smooth, and well incorporated.
06 - Spread half of the meat sauce evenly across the bottom of the prepared crust. Spoon the ricotta mixture over the sauce in dollops and gently spread it into an even layer. Pour the remaining meat sauce over the cheese filling. Finish by sprinkling the remaining 1 cup of mozzarella evenly across the top.
07 - Loosely tent the pie with aluminum foil, ensuring it does not touch the cheese. Bake for 30 minutes. Then carefully remove the foil and continue baking for an additional 15 minutes, or until the cheese is golden brown and bubbling.
08 - Remove from the oven and allow the pie to rest for 10 minutes before slicing. This helps the layers set for clean portions. Serve warm, garnished with additional fresh basil if desired.