Spray potatoes with olive oil spray; and season with salt and pepper.
Transfer potatoes to a baking sheet and roast 12 minutes.
Meanwhile, salt and pepper both sides of chicken. spray a large nonstick skillet with cooking spray and set over high heat. Add chicken and sear 1 minute per side. Add leek, carrots, mushrooms, garlic and herbs; cook 1 minute. Add wine and simmer 1 minute, until liquid reduces to 1/4 cup. Add broth and simmer 5 minutes. Add chard to one side of pan and simmer 1 minute, until chicken is cooked through and greens are wilted.
To serve, place chard in the bottom of 4 bowls. Slice chicken into 5 pieces each and arrange atop chard. Put potatoes and remaining vegetables around chicken and ladle remaining broth on top.