Let's roll. Preheat the oven to 375°F. Toss together cauliflower, onion, olive oil, pepper, and 2 teaspoons of the salt in a big bowl. Spread the resulting mixture in a single layer on 2 rimmed baking sheets, and bake in your preheated oven, stopping to stir halfway through, until cauliflower is tender and lightly browned, about an hour. Remove the sheets from the oven, and let them cool slightly. Process the mixture in a food processor in 2 separate batches. Do this until the mixture is coarsely chopped, but not completely smooth, 30 to 40 seconds per batch. 

Stir together the 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 down the top. Sprinkle the top with remaining thyme, and bake it one last time in the preheated oven until lightly golden on the top, about 20 minutes. Serve hot with crackers, baguette toasts, or whatever other bread-y things tickle your fancy.