Combine coconut milk, soy sauce, fresh lime juice, fresh ginger, Thai chile paste, sugar, and shallots. Reserve 1/2 cup coconut mixture; pour remaining coconut mixture in a zip-top plastic bag. Add chicken breast halves; seal. Marinate in refrigerator 2 hours. Heat a grill pan over medium-high heat. Coat pan with cooking spray. Remove chicken from bag; discard marinade in bag. Sprinkle chicken with salt. Add chicken to pan; cook 7 minutes on each side or until done. Serve with reserved coconut sauce.