FOR THE CALZONE - Preheat oven to 425°F. Heat 1 tablespoon oil in heavy large skillet over medium-high heat. Add mushrooms and fennel seeds; sauté until mushrooms are brown, stirring often, about 5 minutes. Add garlic and oregano; stir 1 minute. Add spinach; stir just until wilted, about 1 minute. Transfer to medium bowl. Season with salt and pepper.
Line rimless baking sheet with parchment. Sprinkle paper with flour. Roll out dough on lined baking sheet to 15 x 10-inch rectangle. Sprinkle Parmesan crosswise over half of crust, leaving 1-inch plain border. Top with Fontina, then mushroom mixture, distributing evenly. Spoon dollops of ricotta cheese over; sprinkle with crushed red pepper. Fold plain half of dough up over filling. Crimp edges tightly to seal. Brush with oil.
Bake calzone until puffed and brown, about 18 minutes. Brush with oil, top with additional Parmesan and serve.