Preheat oven to 425°. Process cauliflower in batches in a food processor until finely ground. Microwave, covered, in a microwave-safe bowl on high until tender, about 8 minutes. When cauliflower is cool enough to handle, wrap in a clean kitchen towel and squeeze dry. Return to bowl., Meanwhile, in another bowl, mix cheeses together. Stir half cheese mixture into cauliflower; reserve remaining cheese mixture. Combine next 6 ingredients; stir into cauliflower., On a baking sheet lined with parchment, shape cauliflower mixture into an 11x9-in. rectangle. Bake until edges are golden brown, 20-25 minutes. Top with reserved cheese; bake until melted and bubbly, 10-12 minutes. Cut into 12 breadsticks. If desired, serve with marinara sauce.