Preheat the oven – Heat to 400 °F (200 °C). Line a baking sheet with parchment paper.
Prepare the dough – Open the croissant dough and unroll it into a rectangle. Separate along the perforations into individual triangles.
Spread the jam – Stir the jam to loosen it. Using a spoon or offset spatula, spread a generous layer of jam over each triangle, leaving a small margin at the wide end. If the jam is very thick, warm it gently to make it easier to spread.
Roll into croissants – Starting at the wide end, roll each triangle toward the point into a croissant shape. Curve the ends slightly to form a crescent.
Egg wash – Place the croissants on the prepared baking sheet. Brush the tops and sides with beaten egg or your chosen glaze. This helps them brown evenly.
Bake – Bake for 12–15 minutes, until the croissants are puffed and deeply golden. The jam may bubble slightly – this is normal.
Finish and serve – Remove from the oven and let cool for a few minutes; the jam will be very hot. Dust with powdered sugar once slightly cooled. Serve warm or at room temperature.
