Heat the oven to 375 F. In a large pan of boiling salted water, simmer the cauliflower for 4 to 5 minutes, or until semicooked. Drain and dry the cauliflower.
In a large bowl, combine the eggs, sour cream, mustard and paprika. Whisk until well-blended. Stir in the chives and 3/4 of the cheeses. Season the mixture with salt and pepper. In a large oven-safe frying pan, heat the olive oil. Fry the cauliflower for 5 minutes, until golden brown on one side. Pour the egg mixture over the cauliflower. Cook over medium heat for 5 minutes. Sprinkle mixture with the remaining cheese, and transfer the pan to the oven. Cook for 10 to 12 minutes or until the frittata is set. Remove from the oven and let frittata sit for 2 to 3 minutes. Cut into 6 wedges.