1 1/4 cups butter, softened
2 cups white sugar
2 teaspoons vanilla extract
2 cups all-purpose flour
3/4 cup unsweetened cocoa powder
1 teaspoon baking soda
1/2 teaspoon salt
2 cups semisweet chocolate chips
Preheat oven to 350 degrees F (175 degrees C).
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Sift together the flour, cocoa, baking soda, and salt; stir into the creamed mixture. Mix in the chocolate chips. Drop dough by teaspoonfuls onto ungreased cookie sheets.
Bake 8 to 9 minutes in the preheated oven. Cookies will be soft. Cool slightly on cookie sheet; remove from sheet onto wire rack to cool completely.