Season chicken with salt, pepper, and paprika. Heat oil in a large skillet over medium-high and brown 3–4 minutes per side; transfer to a plate.
Reduce heat to medium, add butter, then sauté onion and mushrooms until browned, about 6–8 minutes.
Stir in garlic and thyme for 30 seconds. Add chicken broth to deglaze, scraping browned bits.
Whisk in cream and Dijon, simmer until slightly thickened. Return chicken to skillet and cook 5–7 minutes until cooked through.
Taste and adjust seasoning, garnish with parsley, then serve over rice or mashed potatoes.