Preheat the oven to 375°F. Bring a large pot of salted water to a boil and cook the manicotti shells for 6 minutes until just tender. Drain and set aside to cool slightly.

In a mixing bowl, combine the ricotta, 1/2 cup mozzarella, 1/4 cup Parmesan, egg, salt, and pepper. Stir until the mixture is smooth and evenly blended.

Spread 1 cup of marinara sauce across the bottom of a 9x13 baking dish. Spoon the cheese filling into each manicotti shell using a small spoon or piping bag, then arrange the filled shells in a single layer in the dish.

Pour the remaining marinara sauce over the tops of the shells. Sprinkle with the remaining mozzarella and Parmesan.

Cover the dish with foil and bake for 25 minutes. Remove the foil and bake 10 minutes more until the cheese is melted and lightly browned.

While the manicotti bakes, mix the softened butter with minced garlic and parsley. Slice the French bread, spread the garlic butter on each piece, and place on a baking sheet.

During the last 10 minutes of baking, add the bread to the oven and toast until golden at the edges.