Italian Slab Pie

In a large skillet, heat the 1 ½ tablespoons oil over medium-high heat. Add the sausage and cook, breaking up with a wooden spoon, until browned. Transfer to a plate.
Reduce the heat to low. Add the remaining oil, fennel, and garlic; season with salt and pepper to taste. Cover and cook, stirring occasionally, until the vegetables soften, about 5 minutes. Add spinach and stir until wilted. Mix in the sausage.
Preheat oven to 425 degrees Fahrenheit.
In a small bowl, beat the egg with 1 teaspoon water. On a lightly floured surface, roll each puff pastry sheet into a 10×12-inch rectangle. Transfer one sheet to a parchment-lined baking sheet. Top with sausage mixture, leaving a 1-inch border. With a tablespoon, dot with the ricotta, then drizzle with the marinara sauce and sprinkle with half the basil.
Brush the border of the pastry with the egg wash and line up with the remaining sheet of puff pastry, pressing the edges to seal.
Brush the top with egg, and then use a fork to crimp the edges. Cut 4 slits in the top to allow steam to escape. Bake until the pastry is puffed and golden, about 20-30 minutes. Sprinkle with the remaining basil and serve