Preheat the oven to 350 degrees F (175 degrees C).
In a medium bowl, stir together the butter and sugar until smooth. Mix in the egg and vanilla. Combine the flour and baking powder; stir into the batter until a soft dough forms. Divide into 4 pieces.
Shape each piece of dough into a log about 12 inches long. Place on cookie sheet and flatten slightly. Using the round handle of a wooden spoon make an indention all the way down the center of each strip. Fill the indention with preserves.
Bake for 15 to 20 minutes in the preheated oven. Cool slightly before slicing diagonally into 1 inch pieces.