Asparagus Flan with Cheese Sauce

Preparation

1. Make flan:

   Step 1

   Put oven rack in middle position and preheat oven to 325°F. Butter an 8- by 2-inch round cake pan and line bottom with a round of wax paper, then butter paper. 3Steam asparagus in a steamer set over boiling water, covered, until very tender, 6 to 8 minutes. Purée asparagus in a food processor until smooth, 1 to 2 minutes. (You will have about 2 cups purée.)

   Step 2

   Whisk together eggs, milk, cheese, salt, pepper, and nutmeg in a bowl, then whisk in asparagus purée.

   Step 3

   Pour asparagus mixture into pan and bake in a hot water bath until flan is set and a wooden pick or skewer inserted in center comes out clean, 50 minutes to 1 hour.

   Step 4

   Transfer pan to a rack to cool slightly, 10 to 15 minutes.

2. Make sauce while flan cools:

   Step 5

   Put all sauce ingredients in a metal bowl, then set bowl over a pan of barely simmering water. Heat sauce, whisking until cheese and butter are melted, and then stirring with a wooden spoon, until sauce is slightly thickened and registers 165°F on an instant-read thermometer, 5 to 8 minutes. Remove bowl from pan.

3. Step 6

   Run a thin knife around edge of flan to loosen, then invert a serving plate over pan and invert flan onto plate. Remove pan and discard paper. Cut flan into wedges and serve immediately with sauce.