Pastry Cream:

In a heatproof bowl, mix the sugar and egg yolks together. Whisk the flour with the cornstarch and the pumpkin spice, then add to the egg mixture, mixing until you get a smooth paste.

Meanwhile, in a saucepan bring the milk just to a boil (just until milk starts to foam up.) Remove from heat and add slowly to egg mixture, whisking constantly to prevent curdling. (If necessary pour through a strainer.) Then pour the egg mixture into a medium saucepan and cook over medium heat until boiling, whisking constantly. When it boils, keep whisking constantly for another 30 - 60 seconds until the pastry cream becomes thick. Remove from heat and stir in vanilla extract.

Pour the pastry cream into a clean bowl and immediately cover the surface with plastic wrap to prevent a crust from forming. Cool to room temperature then refrigerate until firm (can be made up to 3 days ahead).

Whisk or stir before using to get rid of any lumps that may have formed.

Choux Pastry:

Preheat oven to 400 degrees F (200 degrees C) and place rack in center of oven.

In a bowl whisk the flour with the sugar and salt.

Place the butter and water in a saucepan over medium high heat and bring to a boil. Remove from heat and, with a wooden spoon, add the flour mixture, all at once, and stir until combined.

Return saucepan to the heat and stir constantly until the dough comes away from the sides of the pan and forms a thick smooth ball (about 1-2 minutes). Transfer the dough to your electric mixer (can do this by hand or with a hand mixer), and beat on low speed to release the steam from the dough (about 1 minute).

Once the dough is lukewarm start adding the lightly beaten eggs (dough will separate and then come together) and continue to mix until you have a smooth thick paste (dough will fall from a spoon in a thick ribbon). Spoon or pipe 12 small mounds of dough onto the baking sheet, spacing about 2 inches (5 cm) apart. With a pastry brush, gently brush the tops of the dough with a lightly beaten egg (optional).

Bake for 15 minutes and then reduce the oven temperature to 350 degrees F (180 degrees C). Continue to bake for a further 25 minutes or until the shells are a nice amber colour and when split, are almost dry inside. Remove from oven and place on a wire rack to cool.

To Assemble:

Split the pastry shells in half, lengthwise. Fill the bottom half (spoon or pipe) with the cream. Gently place the top half of the pastry shell on the cream and sprinkle with icing sugar. Can be covered and stored in the refrigerator for two days.