Asparagus Ravioli in Parmesan Sauce

Preparation

1. Make broth and filling while dough stands:

   Step 1

   Cut off asparagus tips, then halve each tip lengthwise and reserve.

   Step 2

   Bring stock, cheese rind, and bay leaf to a simmer in a medium saucepan, then add asparagus stems and cook, uncovered, until stems are just tender, 5 to 6 minutes. Transfer stems to paper towels and cool slightly. Reserve broth.

   Step 3

   Purée asparagus stems in a food processor with grated parmesan, mascarpone, bread crumbs, zest, and 1/2 teaspoon each of salt and pepper.

2. Make Ravioli:

   Step 4

   Cut dough into 4 equal pieces. Cover 3 pieces with plastic wrap, then pat out remaining piece into a flat rectangle and generously dust with flour.

   Step 5

   Set rollers of pasta machine on widest setting. Feed rectangle, a short side first, through rollers. Fold rectangle in thirds, like a letter, and feed it, a short side first, through rollers. Repeat 6 or 7 more times, folding dough in thirds and feeding it through rollers, a short side first each time, dusting with flour to prevent sticking.

   Step 6

   Turn dial to next (narrower) setting and feed dough through rollers without folding, a short side first. Continue to feed dough through without folding, making space between rollers narrower each time, until the second- or third-narrowest setting is used. (Do not roll too thin or pasta will tear when filled.)

   Step 7

   Put pasta sheet on a lightly floured kitchen towel (not terry cloth) with a long side nearest you. Drop 6 rounded teaspoon-size mounds of filling 10 inches apart in a row down center of right half of sheet. Brush pasta around mounds of filling lightly with water, then lift left half of sheet and drape over mounds.

   Step 8

   Press down firmly but gently around each mound, forcing out air. (Air pockets increase the chance that ravioli will break during cooking.) Cut pasta (between mounds) with a sharp knife into roughly 2-inch squares. Line a large shallow baking pan with a lightly floured kitchen towel (not terry cloth), then arrange ravioli in 1 layer in it. Make more ravioli with remaining pieces of dough and remaining filling, transferring to lined pan.

3. Cook ravioli and Asparagus tips:

   Step 9

   Bring a pasta pot of salted water (2 tablespoons salt for 6 quarts water) to a boil over high heat, then reduce heat to a gentle boil.

   Step 10

   Bring reserved broth to a simmer, then simmer asparagus tips, uncovered, until tender, 2 to 3 minutes. Season broth with salt, then divide broth and asparagus tips among 6 shallow bowls, discarding cheese rind and bay leaf.

   Step 11

   Add half of ravioli to gently boiling water, carefully stirring to separate, and cook, adjusting heat to keep at a gentle boil, until pasta is just tender, 2 to 3 minutes. Lift cooked ravioli with a slotted spoon, draining well over pot, then transfer to bowls with broth. Repeat with remaining ravioli.