Heat oven to 375F. Cut French bread in half lengthwise. Reserve one half for another use. With the other half, (I used the bottom) pull out some of the bread from the center, making sure not to go all the way through. Place on a baking sheet and cook in the oven until lightly toasted, just a few minutes.

Meanwhile, heat olive oil in a large skillet over medium-high heat. Add the ground beef and cook until browned. Add in the onion and garlic and cook for a minute or two. Add the tomato paste, tomato sauce, thyme, and oregano and season with salt and pepper. Stir together, reduce heat, and simmer for 20 minutes.

In a bowl, combine the ricotta, Parmesan, egg yolk and parsley. Season with salt and pepper.

Spread the ricotta mixture over the toasted bread. Top with the meat mixture, then a layer of fresh mozzarella. Bake until golden and bubbly, 15-18 minutes. Top with fresh basil, if desired.