Use jams or jellies of different flavors to fill these chewy cookies.
In a large mixing bowl, cream together the butter and sugar. Add the eggs and vanilla, and mix well. Sift together the flour, baking powder, baking soda and salt; add to mixture. Stir until well blended. Refrigerate dough until firm.
Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets.
Roll dough into 1-inch balls and roll in crushed corn flakes. Place on cookie sheets, about 2 inches apart. Indent the center of each ball with your thumb and fill with jam or jelly.
Bake for 15 to 20 minutes in the preheated oven, or until firm.