Heat olive oil in a large skillet over medium-high heat.
Season chicken with salt and pepper and add to skillet.
Cook chicken for about 8 minutes, turning occasionally to brown evenly
Remove chicken to a plate.
Turn heat to low and add butter to skillet.
When butter is melted, add onion and cook until soft.
Add mushrooms and cook until soft and browned.
Turn heat to high and add vinegar, bringing to a boil and scraping the pan to get all of the browned chicken bits.
Reduce heat and simmer for ten minutes. Stir in yogurt and Dijon mustard.
Add chicken and simmer until chicken is heated through.
Sprinkle with parsley and serve over hot egg noodles.
Notes
Cooking time is approximate, and it's more important to cook the chicken until it is no longer pink inside, or to an internal temperature of 170°. Calorie count does not include noodles and broccoli.