Heat 1 Tbsp oil in a large skillet over medium high heat.
Season the chicken with some salt and pepper, and cook in skillet until golden on all sides.
Remove from pan and set aside.
Adding the last Tbsp. of oil to the pan, cook saute the onion, carrots and celery with 1 tsp season salt and 1/2 ts pepper until slightly softened (3-5 min)
Add the garlic and marjoram and stir to combine.
To the vegetables, add the soup and soup cans of milk stirring thoroughly.
Place chicken back into pan and bring to a boil.
Once boiling reduce heat and simmer for about 10 minutes until begins to thicken.
Add butter and parsley and gently stir.
Remove from heat and serve immediately over mashed potatoes.