The pudding can be made the night before.
In a small saucepan set over medium heat, add the milk and maple syrup. Heat the milk until it is scalding (just below boiling - small bubbles will form around the side of the saucepan) - do not boil. Remove from the heat.
While the milk is heating, in a medium bowl add the cream, egg yolk, and corn starch. Whisk until the corn starch dissolves.
Slowly drizzle in about half of the heated milk into the corn starch mixture, whisking constantly. This tempers the egg yolk so it does not scramble. Pour this mixture back into the saucepan with the remaining milk and return to medium heat. Gently whisk constantly until the pudding just starts to thicken - about 2-3 minutes. Remove from the heat.
To the pudding, add the vanilla extract, butter, pumpkin puree, and cinnamon. Whisk until fully incorporated.
Strain the pudding through a fine-mesh strainer set over a medium bowl - be sure to scrape the bottom of the strainer to get all of the pudding! Cover the pudding with plastic wrap set directly on top of the pudding - this keeps a skin from forming. Refrigerate for at least 2 hours - or overnight.
Baking and Assembling - Preheat the oven to 375F degrees and adjust the oven rack to the middle position. Line a baking sheet with a piece of parchment paper.
Remove the cooled chilled dough from the refrigerator and allow to come to room temperature for at least 15 minutes. Lightly flour your work surface. Roll the dough into a 12-inch square. Trim off any rough edges - these an be used to make decorative cut-outs.
Cut the dough into 3-inch x 4-inch rectangles - this will yield 4 Napoleons with 3 pastry sheet layers. You can also cut the dough into any sizes you like - depending on how many Napoleons and how many layers you prefer.
Transfer the dough rectangles to the prepared baking sheet. Brush the top of each lightly with the beaten egg, then sprinkle a healthy amount of cinnamon and sugar on the top.
Bake the pastry sheets for 22-25 minutes, or until they are golden brown. Cool completely on the baking sheet set on a wire rack.
Assembling the Napoleons - place a large dollop (you can also pipe on the pudding if you like) of the chilled Pumpkin Pudding on top of 4 pastry sheets, Top each with another pastry sheet and repeat with the remaining pudding. Finish off with the last pastry sheet and garnish with Whipped Coconut Cream. The Napoleons are best enjoyed the day they are made!