In covered stockpot or large soup pot, bring 12 cups (3 L) water, celery, carrots, onion, garlic, thyme, parsley, bay leaves, salt and peppercorns to boil; reduce heat to low and simmer for 15 minutes.

Add chickens; increase heat and bring to boil. Reduce heat to low to barely maintain simmer; cook, covered, for 50 minutes.

Remove chickens carefully, ensuring skin remains intact; transfer to greased rack on rimmed baking sheet. Let cool for 15 minutes. Brush chickens with oil; let stand for 1 hour. (Make-ahead: Refrigerate, unwrapped, until skin dries, about 3 hours. Wrap and refrigerate for up to 1 day. Bring to room temperature before further cooking.)

Meanwhile increase heat to high; boil until reduced to about 9 cups (2.25 L) liquid, about 30 minutes. Strain, discarding solids. Skim off fat and strain through fine sieve lined with double layer of cheesecloth.

In separate container, reserve 1-¼ cups (300 mL) for Spring Herb Sauce. (Make-ahead: Refrigerate for up to 1 day.)

With pastry wheel or knife, cut noodles into 2- x 4-inch (5 x 10 cm) strips.

In large pot of boiling salted water, blanch snow peas until tender-crisp, about 2 minutes. Remove with slotted spoon. Drain and chill under cold water; drain again. Slice lengthwise into fine strips. Add noodles to water; cook until tender but firm, about 4 minutes. Drain.

Meanwhile, bring remaining broth to simmer; cover and keep hot. Divide noodles among warm soup bowls; top with snow peas. Divide soup among bowls; sprinkle each with 2 tsp (10 mL) cheese. Top with mint. If desired, serve with extra cheese.

Makes 6 to 8 servings.