Remove pastry from the refrigerator, and brush off excess flour. Spread a rectangle of pastry with mustard; sprinkle with both cheeses. Season with pepper. Lay a second pastry rectangle on top.
Place a sheet of parchment on top of the stacked pastry; using a rolling pin, roll until smooth and pastry layers are sealed together. Remove parchment, and brush top of pastry with butter mixture. Chill until firm, about 30 minutes.
With a pumpkin-shaped cookie cutter, cut into 18 to 24 shapes. Immediately place the shapes on a parchment-lined baking sheet. Using a sharp paring knife, score each shape four or five times to make pumpkin ridges. Bake until golden, 15 to 20 minutes.
Transfer puffs to a wire rack; let cool slightly before serving.
—From Martha Stewart Living