How to Make It
Set a medium heatproof bowl over a medium saucepan filled with 1-inch of gently simmering water. Add the egg yolks and whisk until foamy. Add the water and whisk until light and foamy and slightly thickened. Working in batches, whisk in the butter; adding more as each batch melts. Continue whisking until the sauce is thick. Remove from the heat, whisk in the lemon juice and season with salt, black pepper and cayenne.
Melt the butter in a medium saucepan. Add the shallot and cook over moderate heat until softened. Add the morels and cook until heated through. Add the heavy cream and bring to a boil. Add the vin jaune and season with salt and pepper. Stir in the Hollandaise Sauce and set aside.
In a large pot of boiling salted water, blanch the asparagus until just tender. Drain well and pat dry. Arrange the asparagus on plates, spoon the morel hollandaise sauce on top and serve.