Rainbow Puff-Pastry Tarts

On a lightly floured surface, gently roll out and trim dough into two 9-inch squares, 1/8 inch thick, being careful not to press too hard around the edges. Cut out (and reserve) eight 1-inch-wide strips (4 from each square), 1 from each edge. Dough squares should be about 7 by 7 inches. Transfer squares to a parchment-lined baking sheet.

Pierce dough squares all over with a fork. Using a pastry brush, moisten dough edges with beaten egg, being careful not to let any drip down over the cut edges.

Lay reserved 1-inch strips over edges of each square, positioning them to line up exactly, overlapping at corners. Trim strips to fit, if necessary. Brush egg wash underneath each of the 4 overlapping corners to seal them together. Brush tops of strips, being careful not to let egg wash drip down sides. Refrigerate or freeze until firm, about 30 minutes.