Roll dough into a 12-inch circle on a lightly floured surface. Place the dough on a (12-inch) pizza pan or baking sheet coated with cooking spray and sprinkled with cornmeal. Crimp the edges of the dough with fingers to form a rim.
Heat oil in a large nonstick skillet over medium heat. Add leek; sauté for 10 minutes. Cool to room temperature.
Combine cheeses, salt, pepper, and garlic in a bowl. Spread the cheese mixture over pizza crust, leaving a 1-inch border. Top with the leek mixture, and sprinkle with walnuts. Bake at 450° for 15 minutes or until lightly browned. Cut into 8 wedges.