1/2 c. unsalted butter
3 egg yolks
1 1/2 tbsp. lemon juice

Microwave on high 20 seconds to soften butter but not melted. Mix egg yolks and lemon juice, add to butter. Microwave on high 1 minute, whipping every 15 seconds. Butter may be lumpy after first 2 whippings but will smooth out.

Sauce is done when it is smooth and thick, further cooking will cause the sauce to separate or curdle.

Put 2 tablespoons of milk in glass dish, microwave on high 30 seconds to boil. Slowly whisk into curdled sauce until sauce becomes smooth again.