2 tablespoons unsalted butter
1 tablespoon olive oil
2 cups chopped yellow onion (from 1 large onion)
1 cup chopped carrots (from 2 medium carrots)
1 cup chopped celery (from 2 large stalks)
1 ¾ teaspoons kosher salt
3 tablespoons all-purpose flour
4 cups unsalted chicken stock, more if soup is too thick
2 cups whole milk
4 ounces uncooked whole-wheat egg noodles
3 cups coarsely chopped rotisserie chicken breast (from 2 rotisserie chickens)
1 cup frozen green peas
Melt butter with olive oil in a large Dutch oven over medium-high heat. Add onion, carrots, celery and salt and cook, stirring often, until vegetables are slightly softened, 6 to 8 minutes. Add flour and stir to coat. Stir in broth and milk and let mixture come to a boil. Add uncooked noodles to boiling mixture. Cover and cook until noodles are al dente, about 8 minutes. Stir in chicken and peas and cook until pasta reaches desired doneness and chicken and peas are warmed through, about 1 to 2 more minutes. Serve immediately.