Double-Chocolate Raisin and Chip Cookies

Raisins as well as chocolate bits embedded in a rich chocolaty dough distinguish these particular members of the chip-cookie tribe. The recipe can be varied—you might want to omit the cocoa from the dough (increase the flour by 2 tablespoons if you do that), and nuts can be substituted for (or added to) the raisins in either the dark or pale cookies.