Preheat the oven to 375°F (190°C).,Cook the paccheri pasta in salted boiling water according to the package instructions, until al dente. Drain and set aside.,In a medium bowl, combine the ricotta cheese, chopped parsley, grated Parmesan, and the beaten egg. Season with salt and pepper to taste.,Fill each cooked paccheri pasta tube with the ricotta and parsley mixture using a spoon or piping bag.,In a large oven-safe baking dish, spread a thin layer of tomato sauce on the bottom.,Arrange the stuffed paccheri in a single layer over the tomato sauce.,Top the stuffed pasta with the remaining tomato sauce and drizzle with olive oil.,Cover the baking dish with aluminum foil and bake for 20 minutes.,Remove the foil and bake for an additional 10 minutes, or until the top is golden and bubbly.,Garnish with fresh basil leaves, if desired, and serve warm.