Preheat oven to 375 F. Melt chocolate chips in top section of double boiler over hot, not boiling, water, stirring constantly. Remove from heat. Crush Frosted Flakes to make 1½ cups. Sift together flour, soda and salt. Measure margarine and sugar into mixing bowl; beat until very light and fluffy. Add eggs and vanilla; beat well. Add dry ingredients; mix thoroughly. Fold in crushed Frosted Flakes. Swirl warm melted chocolate lightly through batter, leaving streaks of chocolate. Drop by level tablespoonfulls onto ungreased baking sheets. Bake 12 minutes. Remove immediately from baking sheets to cool on wire racks.