In a medium bowl, combine flour, soda and salt. Mix well and set aside.
In a large bowl with an electric mixer, blend sugars at medium speed. Add butter and mix to form a grainy paste, scraping down the sides of the bowl. Add egg, liqueur and banana, and beat at medium speed until smooth. Add flour mixture, 1 cup of the chocolate chips and walnuts, and blend at low speed until just combined.
Drop by rounded tablespoons onto ungreased cookie sheets, 2 inches apart. Sprinkle each cookie with chocolate chips, 6 to 8 per cookie.
Bake at 300°F for 25-27 minutes or until cookie edges begin to brown. Transfer immediately to a cool surface.