Cut chicken thighs into one to two-inch pieces and add to a medium-sized bowl. In a small bowl whisk together flour, coarse kosher salt and pepper. Pour the flour mixture over your cubed chicken and toss until all the chicken is well coated.
Add olive oil to your slow cooker over medium-high heat if your slow cooker has a saute function, if not add to a large skillet. Cook the chicken until lightly browned on all sides, about 4 minutes per side before removing from the slow cooker or skillet to a plate.
Add onions, carrots, celery and garlic to slow cooker or skillet and cook over medium heat for 6-7 minutes, stirring often.
Add broth and chicken with any juices to the slow cooker. Cover and cook on high for two hours. Don't worry, I know it will look like a lot of liquid, but you'll be cooking the noodles in it later in the recipe, so the noodles will soak up the liquid.
Add your uncooked noodles, peas, fresh thyme and rosemary and mix until well combined. Turn the slow cooker temperature down to low and continue to cook for 30 minutes.