Assorted fillings (I used nutella, apricot preserves, and blackberry jam)
In a large bowl, cream together the butter and sugar until smooth. Beat in the eggs one at a time, then stir in the orange juice and vanilla. Mix in the baking powder, then gradually stir in the flour until the dough forms a ball. Cover and refrigerate at least 2 hours. Preheat the oven to 375 degrees F (190 degrees C). Grease cookie sheets. On a lightly floured surface, roll the dough out to 1/4 inch thickness. Cut into 3 inch circles using a cookie cutter or drinking glass. Place circles on the prepared cookie sheets. Spoon 1 teaspoon of filling onto the center of each circle. Pinch the sides of each circle to form a triangle, covering as much of the filling as possible. The cookies may be frozen on the cookie sheets if desired to help retain their shape while cooking. Bake for 8 to 10 minutes in the preheated oven, until light golden brown. These are best undercooked slightly. Cool on the baking sheet for a few minutes before removing to wire racks to cool completely.