Saint Patrick's Pistachio Cookies

I found this recipe at the King Arthur Flour website:

1/2 cup(1 stick) butter,1/2 cup granulated sugar1/4 cup , vegetable oil,1/4 cup water,1 large egg, 2 packages (3.4-oz. each) pistachio instant pudding mix, Jell-O brand preferred*1/8 teaspoon pistachio flavor OR 1 teaspoon vanilla ( I used the vanilla extract),1/2 teaspoon salt,1 teaspoon baking powder,2 cups King Arthur Unbleached All-Purpose Flour,1/2 to 2/3 cup chopped pistachios( i did not use the extra nut as these cookies are great without them)*Jell-O gives the best color. Your cookies won’t be nearly as green if you use a store brand.
Preheat the oven to 350°F. Lightly grease (or line with parchment) two baking sheets. Beat the butter, sugar, and vegetable oil in a bowl till combined, then add water and egg, beating until smooth. The mixture will look curdled at first, but will become creamy as you beat. Add the pudding mix, pistachio flavor, salt, and baking powder, beating until smooth; the mixture will turn a lovely pastel green. Stir in the flour and nuts. Drop the dough by the tablespoonful (a tablespoon cookie scoop works well) onto the prepared baking sheets, leaving about 2" between cookies. Flatten the cookies, if desired, using a fork, the flat bottom of a drinking glass, or the end of the pusher from your food processor. If you don’t flatten the cookies, they’ll bake up in softly flattened mounds; they’re lovely either way. Bake the cookies for 15 minutes, until they’re starting to brown on the bottom. Remove them from the oven, and cool right on the pans.Yield: about 32 cookies.