Preheat the oven to 350°F (177°C). Line two baking sheets with parchment paper or a silicone baking mat.

Whisk the egg and water in a small bowl, then set aside.

Lightly flour your work surface. Unfold the pastry sheet, then lightly dust the top with flour.

Use a rolling pin to roll the sheet into a 16-inch square. Cut the pastry square in half, then cut each half into four rectangles, making eight 8-inch by 4-inch rectangles. Cut each rectangle diagonally into two triangles, making 16 triangles.

Place 2 teaspoons of the chocolate chips down the center of each triangle.

Starting at the wider end, roll each triangle up.

Place each croissant seam-side down so that the tip of the triangle is tucked under the rolled croissant. Bend in the edges, creating a crescent shape.

Lightly brush the tops of croissants with egg wash.

Bake the croissants until they are golden brown, 20 to 25 minutes.