01 - Preheat oven to 375°F. Roll out the pie crust and press it into a 9-inch pie dish. Trim any overhang and flute the edges. Prick the bottom lightly with a fork to prevent puffing. Set aside.
02 - Heat olive oil in a large skillet over medium heat. Add ground beef and cook, breaking it apart with a spoon, until browned and cooked through, about 5 to 7 minutes. Drain excess fat if needed.
03 - Add diced onion and minced garlic to the skillet. Cook until softened, about 3 minutes. Stir in marinara sauce, dried oregano, salt, and pepper. Simmer for 5 minutes to meld the flavors. Remove from heat.
04 - In a medium bowl, combine ricotta cheese, egg, 1 cup of mozzarella, Parmesan, chopped basil, and red pepper flakes. Mix until smooth and creamy.
05 - Spread half of the meat sauce evenly over the bottom of the prepared crust. Dollop the ricotta mixture over the sauce and gently spread into an even layer. Top with the remaining meat sauce, then sprinkle the remaining 1 cup of mozzarella over the surface.
06 - Loosely tent the pie with aluminum foil. Bake for 30 minutes, then remove the foil and continue baking for 15 more minutes until the cheese is golden and bubbly.
07 - Allow the pie to cool for 10 minutes before slicing to set the layers. Serve warm, garnished with additional fresh basil if desired.