Preheat the oven to 425 degrees F.
Place the chicken on a rimmed sheet tray and drizzle with the olive oil. Sprinkle liberally with salt and pepper. Roast until the chicken registers 160 degrees F, 35 to 40 minutes. Remove from the oven and let cool slightly. Remove and discard the skin, shred the chicken and set aside.
Melt the butter in a large pot over medium-high heat. Add the carrots, celery and onions and cook just until the vegetables begin to soften, about 3 minutes. Sprinkle with salt and pepper. Add the garlic and cook 1 minute longer. Add the chicken broth and bring to a simmer.
Add the egg noodles to the simmering stock and continue cooking until the noodles are cooked through, about 10 minutes. Return the chicken to the pot along with petite peas and fresh thyme and heat through before serving. Adjust the seasoning with salt and pepper if necessary.