Preheat oven to 350*F (175*C). In large mixer bowl, cream butter and sugar until light and fluffy. Add eggs and vanilla; beat well. Sift together flour, cocoa, baking soda, and salt; gradually blend into creamed mixture. Stir in chocolate chips. Drop by spoonfuls onto ungreased cookie sheets. Bake 8 to 9 minutes. DO NOT over bake! Cookies will be soft. Cool slightly on cookie sheet; transfer from sheet onto wire rack to cool completely.
1 1/4 cups butter or margarine, softened – 2 cups granulated sugar – 2 large eggs – 2 teaspoons vanilla extract – 2 cups all-purpose flour – 3/4 cup unsweetened baking cocoa – 1 teaspoon baking soda – 1/2 teaspoon salt – 2 cups chocolate chips