1/2 cup (1 stick)butter or margarine, cut into pieces
1 1/4 cups all-purpose flour
1 cup granulated sugar
1 teaspoon vanilla extract
1/4 teaspoon baking soda
1/2 cup chopped nuts (optional)
Preheat the oven to 350° F. Grease 13 x 9-inch baking pan.
Melt 1 cup of the chocolate chips and butter in large, saucepan over low heat; stir until smooth. Remove from heat. Stir in eggs. Stir in flour, sugar, vanilla extract and baking soda. Stir in the remaining chocolate chips and nuts. Spread into prepared baking pan.
Bake for 18 to 22 minutes or until wooden pick inserted in center comes out slightly sticky. Cool completely in pan on wire rack. Cut into bars.