Double-Chocolate Cookies

The secret of this rich chocolate chip cookie is not to over-bake it. For a sticky, creamy cookie core, remove them from the oven when they are still slightly shiny.
Spoon the flour into dry measuring cups; flatten with a knife. Combine flour, cocoa and salt in a bowl, stirring with a whisk.Put the sugar, butter and vegetable oil in a bowl; beat with a mixer on medium speed until smooth (about 5 minutes). Add the eggs, 1 at a time, beating well after each addition. Add vanilla; beat for 1 minute. Add the flour mixture to the butter mixture, beating on low speed until smooth. Add the chocolate; beat on low speed until smooth. Cover with plastic wrap; refrigerate 30 minutes.Preheat the oven to 350 degrees.Place the dough 1 1/2 tablespoons apart, 2 inches apart, on baking sheets lined with parchment paper. Bake at 350 ° C for 8 minutes or until almost cooked through. Cool on a baking sheet for 2 minutes or until firm. Remove the cookies from the pan; cool on a wire rack.