Preheat the oven to 400 degrees F. Lightly dust a baking sheet and work surface with flour.
Roll the dough into a rectangle about the size of the baking sheet (13 by 18 inches).
In a large bowl, combine the spinach, mozzarella and garlic. Toss to combine. Evenly sprinkle over the dough, leaving about a 1-inch border all the way around. Dot the mixture with the ricotta cheese and sprinkle with salt and pepper.
Roll the dough into a log, starting at a short end. Tuck any filling that may have fallen out back into the roll. Transfer the log seam-side down to the prepared baking sheet. Drizzle with olive oil and bake until golden brown and puffed, 25 to 30 minutes.
Remove from the oven, let cool slightly, then slice into rounds and serve with marinara sauce.