Melt over hot (not boiling) water, 3/4 cup mint-chocolate morsels. Stir until smooth. Remove from heat. Cool.
In bowl, combine flour, baking soda, and salt, set aside.
In bowl, combine butter, brown sugar, sugar, and vanilla. Beat until creamy. Add melted morsels and egg, beat well. Gradually blend in flour mixture.
Stir in remaining 3/4 cup mint-chocolate morsels and nuts. Drop by rounded tbsp. onto ungreased cookie sheets.
Allow to stand 2-3 minutes before removing from cookie sheets.