1 cup butter
1 cup brown sugar
1 1/2 cups white sugar
1 egg
1 teaspoon corn syrup
1 cup all-purpose flour
1 teaspoon baking soda
3/4 teaspoon baking powder
1/4 teaspoon salt
1 cup marshmallows
Preheat oven to 350 degrees F (175 degrees C).
In a large bowl, cream together the butter and brown sugar until smooth. Beat in the sugar, egg, corn syrup and flour. Mix in baking soda, baking powder and salt. Beat in marshmallows. Drop by rounded spoonfuls onto ungreased cookie sheet.
Bake for 8 minutes in the preheated oven. Cookies may crack when carefully placed onto the cookie sheet. Allow cookies to cool on baking sheet for 10 minutes before removing to a wire rack to cool completely.