Prepare the pie crust

1. In a stand mixer with a paddle attachment, beat the softened butter until creamy.
2. Add salt, egg yolk, and vanilla extract (if using). Mix until combined.
3. Gradually add the flour and almond powder. Mix until the dough resembles coarse crumbs.
4. Slowly pour in the warm water and mix just until the dough comes together. Do not over-mix.
5. Turn the dough out onto a lightly floured surface. Roll it out rather thinly.
6. Line the 22 cm tart pan with the pastry, pressing it gently into the edges. Trim any excess dough.
7. Place the tart shell in the freezer for at least 30 minutes (or until ready to use, you can pre-prepare it).

Prepare the custard filling

1. Infuse the milk : In a saucepan, combine the milk, heavy cream, vanilla extract, and pumpkin spice. Bring to a gentle boil.
2. Remove from heat, cover, and let it infuse for at least 30 minutes (or overnight for a stronger flavor).
3. In a stand mixer, whisk the egg yolks and sugar until pale, thick, and very very fluffy (about 5-7 minutes).
4. Add the cornstarch and mix until fully incorporated.
5. Slowly pour the warm (not boiling) infused milk into the egg mixture while whisking continuously.
6. Return the mixture to the saucepan and cook over medium heat, stirring constantly, until it thickens and comes to a boil once.
7. Remove from heat and stir in the butter and crème fraîche until smooth.
8. Let the filling cool slightly (about 10 minutes).

Assembling and Baking

1. Pour the filling into the chilled tart shell, leaving about ½ cm (¼ inch) of space below the rim to prevent overflow during baking.

Baking

1. Preheat the oven to 160°C (320°F) with convection (fan-assisted).
2. Bake the tart for 50-60 minutes, or until the top is golden brown and the filling is more set (it will only fully set while cooling).

Chilling

1. Remove the tart from the oven and let it cool to room temperature.
2. Refrigerate for at least 6 hours to allow the filling to set and develop a creamy texture.

Preparation Pumpkin Topping

1. Cut the Pumpkin into small cubes.
2. Make a sugar syrup: Bring the water and brown sugar and spices in a pan to a boil in a pan. Let it boil until the sugar is well dissolved and then add the pumpkin. Let it cook until the pumpkin is very soft.
3. Put the mixture into a blender and blend it as smooth as possible.
4. Let it cool a little and then spread over the top of the finished flan.
5. Let the topping cool before serving.

Enjoy your Pumpkin Spice Flan !