EASY HOLLANDAISE SAUCE IN A BLENDER
8 to 16 tablespoons unsalted butter
2 large egg yolks
1 tablespoon lemon juice
1/4 teaspoon salt
Pinch cayenne, optional
Melt the butter: Use 8 tablespoons of butter for a thick hollandaise for dipping or dolloping; use up to 16 tablespoons to make a thinner, pourable sauce.
Unwrap the butter, cut it into a few large pieces, and transfer it to a microwave-safe measuring cup. Microwave in 30-second bursts until the butter has completely melted. Use the butter when it is no longer piping hot, but is still very warm; if it has set for too long and is no longer warm, re-warm the butter in the microwave. (Alternatively, melt the butter in a small saucepan over medium-low heat.)
Blend the yolks, lemon juice and salt: Combine these ingredients in a blender and pulse to combine.
With the blender running, slowly stream in half the warm butter: Start the blender running and leave the top open. Slowly stream in the warm butter — start with a few drops, then a thin drizzle. Once you've added about half the butter you want to add, check the sauce (you can stop the blender if you need to).
Continue adding butter in a steady stream: If the sauce is looking good, you can pour the butter a little more quickly in a steady stream. Continue pouring the butter and occasionally checking the sauce until the sauce is as thick or thin as you'd like, or you've added all the butter. When done, the hollandaise should be light yellow with a smooth, uniform consistency.
Taste and adjust the sauce: Stop the blender and taste a small spoonful. It should taste rich, buttery and slightly tangy. Stir in a little salt, cayenne, or lemon juice, if needed. If the sauce seems a little too thick to you, blend in some water a tablespoon at a time until the sauce is as thin as you like it. Makes about 1 cup, serves 4 to 6.
Serve the sauce: Hollandaise is best served as soon as it's ready, while still warm. If you need to, you can transfer the sauce to a double-boiler and keep it warm over low heat on a back burner, or set over a bowl of very hot water, for about an hour. The thicker and more mayonnaise-like the hollandaise, the more stable it tends to be; thinner sauces will break more easily — especially if they are held for too long before serving or if they get too cool.