Beat the butter and sugar until smooth in a mixing bowl. Add the remaining wet ingredients. Mix thoroughly.
Sift the flour, baking powder, and salt together. Mix in a little at a time until a firm dough forms. If it is still a little wet and sticky, you can add a little more flour.
Wrap the dough in plastic and refrigerate for at least an hour, up to a full day.
Preheat oven to 400.
Remove the dough from the fridge. Flour a surface and roll out the dough to about 1/8 to 1/4 inch thick. Cut out circles with a round cutter or whatever is clever. Place a dollop of jam in the middle of each circle. Then, pinch in the corners on three sides to make a triangle. Refrigerate for another 10 minutes.
bake for about 8 to 10 minutes until just slightly browned and firm. Cool and serve.
Notes
Traditional fillings are apricot or berry jams. But, you can play with the fillings. Try a cheesecake filling or ricotta for a cannoli variation. You could do lemon curd, or a myriad other variations.