Flatten package of crescent rolls into 13 x 9 inch pan or cookie sheet. Mix 2/3 cup butter and 2/3 cup brown sugar in small saucepan; boil 1 minute. Add 1 cup walnuts or pecans, chopped. Pour over rolls. Bake 14-18 minutes in 350-375 degree oven. Spread with 1 cup chocolate chips immediately after taking out of oven. (Very good.)