Use a large microwave-safe glass bowl — the mixture bubbles up significantly. Do not use plastic. Whisk mixture until fully smooth before microwaving. Salt and vanilla go in AFTER microwaving — not before. Sauce looks thin when hot; it thickens as it cools. If too thin after cooling, microwave in 30-second increments. Refrigerates up to 2 weeks; reheat 20-25 seconds to restore pourable consistency.