In the bowl of an electric mixer (this can also be done by hand), combine all ingredients.
Refrigerate dough for at least 30 minutes before forming cookies.
Meanwhile, prepare the streusel. In a bowl, combine 1 cup flour, sugar, and oil. Add a couple tablespoons more flour and mix until mixture is crumb-like.
Preheat oven to 350°F. Roll cookies into balls and place on lined baking sheets. Top generously with streusel. Bake for 15 minutes.