If frozen, set out puff pastry sheets to slightly thaw, up to 40 minutes. They should remain cold but be pliable enough to roll out.
Preheat oven to 400°F degrees
Mix together the 2 tablespoons of granulated and 1 teaspoon of the pumpkin pie spice, set aside.
Mix together the pumpkin puree, 1 whole egg, brown sugar, 1 teaspoon of pumpkin pie spice, the vanilla, salt and half and half. Whisk until well combined, set aside.
Roll out the puff pastry sheets so they are about 13 inches long (big enough to do 3 rows of pumpkins). Use a pumpkin shaped cookie cutter to cut the puff pastry into pumpkin shapes. Place 12 of the puff pastry pumpkins on two baking sheets lined with parchment paper.Use a small, sharp knife to cut out Jack O' Lantern faces in the remaining 12 pumpkins. Use a rolling pin and roll over each Jack O' Lantern once or twice to make it just slightly larger than the bottom pumpkin.
Spoon about 1 tablespoon of the pumpkin pie mixture onto the center of each pumpkin bottom. Use your finger to brush the edge of the puff pastry with water. Carefully set the Jack O' Lantern Pumpkin on top, lining it up with the pumpkin on the bottom. Use your finger to gently press together the edges of the pumpkins.
Whisk the egg yolk with one tablespoon of water. Brush the egg wash over the tops of the pastries. Sprinkle with the sugar and spice mixture.
Bake for 15 minutes, until the pumpkins are puffed and golden.