Place a large pot of salted water over high heat and bring to a boil. Cook the pasta until al dente according to package directions. Drain thoroughly, return it to the pot and toss with 1 tablespoon butter and parsley. Set to the side.
While the pasta is cooking, place a large skillet over medium-high heat with one turn of the pan of EVOO, about 1 tablespoon. Add chicken to the pan, season with salt and pepper and lightly brown. Remove chicken from the pan and add onion, celery, carrot, parsnips and bay leaf. Cook until tender, about 3-4 minutes.
Scoot all the veggies to one side to create some space on the bottom of the pan. Melt 1 tablespoon butter and stir in flour. Cook about 1 minute then stir in Dijon mustard and chicken broth and bring up to a bubble. Add in sage, peas and toss the browned chicken back in. Cook until chicken is cooked through and broth is thickened, about 3-4 minutes.
Serve chicken on top of buttered parsley noodles.