This was my great aunt's recipe. If you like thick and chewy cookies then these are unbeatable. There is no white sugar and both light and dark brown sugar are used. White sugar will dry out a cookie where brown sugar has a much higher moisture content.

1 cup unsalted butter at room temperature
1 cup dark brown sugar, packed
1 cup light brown sugar, packed
1 tablespoon vanilla extract
2 eggs
1 teaspoon baking soda
2 1/2 cups all-purpose flour
1 1/2 teaspoons salt
3 cups semi-sweet or bittersweet chocolate chips

Follow creaming method. Chill and then drop by 1/3 cup on lined baking sheet. Bake at 375 for 10-12 minutes.