Preheat the oven to 375 F.
Roll out one piece of dough on a floured surface so it's about ⅛-inch thick. Use the rim of a juice/rocks glass to cut out 3-inch circles. Repeat with the remaining dough; you may need to form it into a ball again and then roll it out to use as much dough as possible.
Spoon a teaspoon of jam into the center of each dough circle.
With your fingers, gently fold the edges of each dough circle to form a triangle, pinching each one at three corners to keep the filling in but leaving the center slightly exposed.
Arrange the cookies on 2 large baking sheets and bake them for 8-10 minutes until the stat to lightly brown.
Cool them on a baking sheet for a couple minutes before moving them to a wire rack to cool completely. Store them in an airtight container for up to 5 days.