Preheat oven to 350F. Bring the salted water to a boil. Cut off the outside leaves of the cauliflower, use knife to cut out the core with a large V. Cut into large florets. Drop into boiling water, cooking til soft, about 10 - 15 minutes. Drain well in a colander. Meanwhile, heat a small skillet on MEDIUM, add the 1 tablespoon of butter and let melt til shimmery. Add the onion, garlic and bouillon and let cook til onions are just beginning to turn brown. Combine the onion mixture, cooked cauliflower and sour cream in a food processor and process til smooth. Add the 2 tablespoons of butter and process til smooth. Transfer to a well-greased baking dish and bake til hot all the way through, 15 - 20 minutes.