First, prepare the coconut coating. Combine the freshly grated coconut with salt and pandan leaf, then steam for about 10 minutes. Remove the pandan and set the coconut aside while you prepare the klepon.
Place the mashed pumpkin, glutinous rice flour, and salt in a large bowl. Mix and gently knead until a soft, pliable dough forms. The pumpkin already contains quite a bit of moisture, so don't immediately add water. If the dough feels too dry or cracks when shaped, add water a little at a time until it can easily be rolled into balls.
Lightly dust a tray with glutinous rice flour.
Take a small portion of dough and roll it into a ball. Flatten it gently in the palm of your hand, place a small amount of chopped palm sugar in the center, then carefully bring the edges of the dough around the filling.
Pinch the seam completely closed before rolling it gently between your palms to create a smooth ball.
This part matters. If there are cracks or openings in the dough, your beautiful molten palm sugar may escape into the cooking water instead of waiting for you inside the klepon.
Continue shaping until all of the dough has been used.
Bring a large pot of water and the knotted pandan leaves to a boil. Carefully add the klepon, working in batches if necessary so they have enough room to move.
Cook over medium heat until the klepon float to the surface.
Once they float, continue cooking for approximately 3 minutes. This gives the dough time to cook completely and allows the palm sugar inside to melt.
Remove the klepon with a slotted spoon and let the excess water drain briefly.
While they're still warm and slightly damp, immediately roll them in the steamed grated coconut until completely coated.
Serve warm or at room temperature.