Place a large Dutch oven or heavy-bottomed stockpot over medium-high heat. Add the vegetable oil and one tablespoon of the unsalted butter.
Season your cubed chicken breasts with salt and pepper. Once the butter is foaming, add the chicken to the pot in a single layer.
Lower the heat to medium and add the remaining tablespoon of butter to the same pot.
Add the diced onion, carrots, and celery.
Use a wooden spoon to scrape the bottom of the pot (deglazing), picking up the "fond" or browned bits left behind by the chicken.
Sauté the vegetables for about 6 to 8 minutes until the onions are translucent and the carrots have softened slightly.
Add the minced garlic, dried thyme, and dried oregano.
Cook for an additional 60 seconds until the garlic is fragrant, being careful not to let it brown or turn bitter.
Sprinkle the all-purpose flour over the sautéed vegetables.
Stir constantly for 2 minutes. This "blonde roux" serves as our primary thickening agent. Cooking the flour for these two minutes is essential to remove the "raw" flour taste while ensuring it doesn't brown too much and lose its thickening power.
Slowly pour in the chicken broth, one cup at a time. Whisk or stir vigorously after each addition to ensure the flour incorporates smoothly without forming lumps.
Bring the mixture to a gentle boil, then return the seared chicken (and any juices from the plate) to the pot.
Reduce the heat to low and simmer for 10 minutes.
Increase the heat slightly to maintain a steady simmer and add the wide egg noodles.
Cook the noodles for approximately 6 to 7 minutes, or about 2 minutes less than the package instructions suggest.
Once the noodles are "al dente," reduce the heat to the lowest setting.
Slowly pour in the heavy cream. Stir gently to incorporate.
Allow the soup to heat through for another 2 to 3 minutes, but do not let it reach a rolling boil again.
Taste the soup and adjust the seasoning with additional salt or pepper if needed. Stir in the fresh parsley just before serving.