It took me the longest time to successfully make mayonnaise. My problem was a lack of patience, which made me add the oil too fast. So I paced myself using a teaspoon and voila! I will never buy mayonnaise again!
The more flavorful cousin of hollandaise, lovingly called Bea in Sweden, may be scary to make at first, but surprisingly simple when you get the hang of it. My method does not require a double boiler or clarified butter, just focus and whisking!