These Swedish dream cookies, known as drömmar, are traditional buttery sugar cookies widely eaten in Sweden and other Scandinavian countries. A special ingredient (baker’s ammonia) makes these cookies airy crisp with a cracked surface.
Preheat oven to 300 degrees F. Line two baking sheets with parchment paper. Sift together flour, cornstarch, baker’s ammonia, and salt (if using); set aside.
In the bowl of a mixer, beat together the butter and sugar until light and fluffy, about 2-3 minutes. If mixing by hand, blend the butter and the sugar with a spatula or wooden spoon until they are mixed well. Mix in vanilla. Slowly add the oil to the butter mixture and continue to mix until combined.
Add the flour mixture and continue mixing until well incorporated. The dough will be on the dryer side.
Shape the dough into 24 balls and place them 2 inches apart on prepared baking sheets. Bake for 20-22 minutes, or until firm and cracked on top.
Let cookies cool on baking sheet for 3 minutes and then transfer cookies to a wire cooling rack and let cool completely.