1. Preheat your oven to 375 F (190 C). Line a baking sheet with parchment paper to prevent sticking and make cleanup easier.

2. Carefully unroll the crescent roll dough onto your prepared baking sheet. If using traditional crescent rolls, pinch together the perforations to create two solid rectangles of dough.

3. In a small bowl, gently mix the sourdough discard. Evenly spread half of the sourdough discard over one of the crescent dough rectangles, leaving a small border around the edges.

4. Spoon and spread your chosen fruit jam over the sourdough discard layer on the first dough rectangle. Don’t overfill, or it might seep out during baking.

5. Carefully place the second crescent dough rectangle on top of the jam-covered one. Use your fingers or a fork to firmly crimp the edges all around, sealing the filling inside.

6. Using a sharp knife or a pizza cutter, cut the large rectangle into 6-8 individual pop tart shapes. You can make them rectangular or square. Pierce the top of each pop tart 2-3 times with a fork to create steam vents, which helps prevent them from puffing up too much.

7. Bake for 10-12 minutes, or until the pop tarts are golden brown and puffed. Keep an eye on them, as oven temperatures can vary.

8. While the pop tarts are baking, whisk together the powdered sugar, milk, and vanilla extract in a small bowl until smooth. Adjust the milk amount to achieve your desired glaze consistency – thicker for a more opaque coating, thinner for a lighter drizzle.

9. Once the pop tarts are out of the oven, let them cool on the baking sheet for a few minutes before transferring them to a wire rack. Drizzle or spread the glaze over the warm pop tarts. If desired, add sprinkles immediately before the glaze sets. Serve warm or at room temperature.