Step 1
Peel carrots and add peels to a Dutch oven or other large pot. Trim off ends and leafy tops from celery; add to the pot. Trim dark green stalks from leek; rinse. Cut into 2-inch pieces and place into the pot; add bay leaf and thyme sprigs. Smash and peel 2 garlic cloves and add to the pot.
Step 2
Finely chop the light green and white parts of the leek; rinse and set aside in a medium bowl. Slice carrots into small pieces and add to the bowl. Slice celery on the bias and combine with the carrots and leeks. Mince remaining garlic; set aside separately.
Step 3
Cut away the skin from the chicken breast; set aside. Place chicken in the pot with the vegetable trimmings and pour in broth to cover. Bring to a boil over high heat. Reduce heat to medium-low cover and simmer until an instant-read thermometer inserted into the thickest part of the chicken reads at least 165 degrees F (74 degrees C) 30 to 40 minutes.
Step 4
Remove chicken; discard skin. Wrap chicken to prevent it from drying out. Strain broth and discard vegetable trimmings.
Step 5
Heat a Dutch oven over medium heat; cook chicken skin until lightly crisp and fat has rendered out about 8 minutes. Remove skin and increase heat to medium-high. Add reserved chopped vegetables; cook stirring occasionally until softened and lightly browned 5 to 6 minutes. Add minced garlic and thyme; cook stirring constantly until fragrant about 1 minute.
Step 6
Pour in strained broth; bring to a boil. Reduce heat to medium and simmer uncovered until vegetables are tender about 10 minutes.
Step 7
In the meantime bring a pot of salted water to a boil over high heat. Cook egg noodles at a boil until tender yet firm to the bite 7 to 9 minutes. Drain.
Step 8
Season broth with salt and pepper. Stir in lemon juice; taste and adjust as needed. Stir in shredded chicken and cook until warmed through about 2 minutes.
Step 9
Scoop egg noodles into serving bowls and pour soup on top; garnish with parsley. Serve hot.