Step 1

Preheat oven to 350°. Cream butter and sugar until light and fluffy; beat in egg, oil, vanilla and butter flavoring. In another bowl, whisk together flour, cornstarch, baking powder and salt; gradually beat into creamed mixture.

Step 2

Shape dough into 1-in. balls; place 2 in. apart on greased baking sheets. Press a deep indentation in center of each with the end of a wooden spoon handle. Bake until edges are light brown, 8-10 minutes.

Step 3

Remove from pans to wire racks to cool. Fill with preserves.