Creamy Roasted Cauliflower and Onion Dip

Preheat oven to 375°F. Toss together cauliflower, onion, olive oil, pepper, and 2 teaspoons of the salt in a large bowl. Spread mixture in a single layer on 2 rimmed baking sheets, and bake in preheated oven, stirring halfway through, until cauliflower is tender and lightly browned, about 1 hour. Remove from oven, and let cool slightly. Process in 2 batches in a food processor until coarsely chopped, not completely smooth, 30 to 40 seconds per batch. 

Stir together cauliflower mixture, cream cheese, shredded Swiss, parsley, half of the thyme, and remaining 1/2 teaspoon salt in a medium bowl until combined. Spoon into a lightly greased 2-quart baking dish, and smooth the top. Sprinkle with remaining thyme, and bake in preheated oven until lightly golden on the top, about 20 minutes. Serve hot with crackers or baguette toasts.