Heat about 1 tablespoon of olive oil in a large non-stick skillet over medium heat.
Season both sides of the chicken with salt and pepper and add to the skillet. Cook chicken for about 4 minutes on each side, or until cooked through. Transfer chicken to a plate and tent with foil to keep warm.*
Melt butter in the skillet. Add garlic and mushrooms to the skillet, sautéing until mushrooms are tender (about 4 minutes). I like to scrape up the bits at the bottom of the pan with a wooden spoon as I stir. This gives the sauce so much flavor!
Add flour, salt, and pepper and stir until thick (about 1 more minute). Slowly add the milk, stirring constantly. Stir in the wine (or chicken broth). Bring sauce to a gentle simmer (don’t let it boil), and cook, stirring regularly until it thickens slightly (about 3-4 minutes).
Return chicken to the skillet to warm through. Serve chicken with plenty of mushroom sauce on top and garnish with fresh parsley.
