Asparagus with Blender Hollandaise

Melt butter in a small saucepan over medium heat; let cool about 5 minutes. Put egg yolks in a blender. With motor running, gradually add butter. Add lemon juice and cayenne; season with salt and pepper. (Sauce should be thick but fluid enough to drizzle from a spoon, and should form a pool, not a mound. If too thick, thin with warm water.) Season to taste with lemon juice, salt, and pepper. Sauce is best used immediately, but can be stored in a thermos about 30 minutes.

Meanwhile, bring 1 inch salted water to a boil in a large straight-sided skillet. Add asparagus, in batches if needed to avoid crowding. Cook until crisp-tender, 3 to 4 minutes; drain. Serve warm or room temperature, with sauce.