In a heavy saucepan, heat the butter and olive oil over medium. Add the shallots and garlic, turn the heat down to medium-low, and allow the shallot and garlic to cook gently for about 30 minutes. Stir occasionally, sprinkling the sugar over the shallots and garlic after about 10 minutes. Add the crushed red pepper, basil, and celery seed in the final 5 minutes, stirring 2-3 times.