Using an electric mixer, cream together the butter, granulated sugar, and brown sugar until light and fluffy. Add the egg, vanilla extract, flour, baking soda, and salt and mix until combined. Fold in the chocolate chips.
Divide the dough in half. Place each piece of dough into an ungreased long loaf pan (about 12 x 4.5 inches) that has been lined with parchment paper.
Place the pans in the oven and bake for 20 to 25 minutes. Remove from the oven and leave the cookies in the pan until they set. If you remove the cookies before they set, they will spread.