In a large bowl, combine main ingredients and gently fold together until well mixed. Season with salt and pepper. Coat the interior of a large casserole dish with butter and fill with crab dip mixture. Top with remaining Swiss and Parmesan cheese and sprinkle with smoked paprika. Bake uncovered for about 30 minutes, or until the top is golden brown and bubbly. Serve with your choice of toasted baguette slices, pita bread or even plain tortilla chips.