In a large bowl, lightly cream the margarine and sugars. Add eggs, one at a time, beating well after each addition. Beat in yogurt and vanilla. Combine the flour, baking soda and salt; gradually add to creamed mixture. Stir in chocolate chips and walnuts.
Drop by heaping tablespoonfuls 2 in. apart onto baking sheets coated with cooking spray. Bake at 375° for 8-10 minutes or until golden brown. Remove to wire racks.