On a cutting board, finely dice the onion, and dice the celery and carrots into ½' pieces. For a shortcut you can buy wavy carrot chips that are presliced.
Line a large sheet pan with parchment paper for easy clean up. Place 4 breasts (they can be boneless or split bone in breasts) season with salt and pepper on both sides.
Heat oven to 400 degrees, and bake small breasts bone in for 45 minutes and larger ones for 50-55 minutes. Boneless usually cooks faster, depending on the thickness of them,so check them at 20 mintues. Make sure to read the internal temperature with a good meat thermometer, it is cooked at 160 degrees Fahrenheit.
Let the cooked chicken rest on the sheet pan until cool enough to handle, remove the bones and skin, and dice into ½" pieces.
On medium-high heat, in a large pot or dutch oven, add 3 tablespoons of butter, ½ teaspoon sea salt, and ¼ teaspoon black pepper into the bottom of the pot. Once butter is melted, add onions and cook until soft. Then add the chopped celery and carrots, and cook for 5 minutes. As the vegetables cook, scrape up the browned bits off the bottom of the pot with a wooden spoon.
Add chicken stock and bring to a simmer on medium-low heat. Add the cooked meat and uncooked pasta noodles. One tip is just use as many noodles as you will eat for that meal. Save the leftover soup without noodles in it, otherwish the noodles get soggy.
Squeeze ½ a lemon into the soup, you will be amazed how this brightens up the flavor!
Cook for about 10 minutes until the noodles are cooked. Ladle into soup bowls and serve with crackers, breadsticks, or homemade bread.
Reheast leftover soup back on the stove in a pan with more dry noodles the next day. You can freeze soup in an airtight container for up to 3 months.