Melt chocolate and butter in a 2-quart saucepan over low heat, stirring frequently; stir in sugar and set aside to cool slightly.
Preheat oven to 350°F. Grease a 9 x 9-inch baking pan. Add eggs, one at a time, to chocolate mixture in saucepan, beating well after each addition. Stir in flour and TABASCO® Sauce and mix well. Stir in chocolate chips and walnuts. Pour mixture into pan. Bake 35 to 40 minutes or until toothpick a inserted in center comes out clean. Cool completely in pan on wire rack; cut into squares.
Makes 16 brownies.