Begin by selecting a large mixing bowl.

Let's start with the pie crust preparation. Pour 1 cup of hazelnut flour into the mixing bowl.

Add 1/4 cup of almond flour and 1/2 teaspoon of cinnamon.

Incorporate 1/4 teaspoon of nutmeg, a pinch of salt, and 1/4 cup of powdered sweetener.

Set the mixture aside without mixing.

Now, use a small bowl and pour 6 tablespoons of melted butter into this bowl.

Add 1/4 teaspoon vanilla extract and stir well.

Combine the previously set aside flour mixture, then add the butter mixture to it. Stir everything thoroughly until well mixed.

Prepare a baking tray and evenly spread the mixture onto it.

Bake in a preheated oven for 15 minutes.

While the crust is baking, start on the filling.

Peel the pumpkin and chop it into cubes to make 3 cups of pumpkin cubes. Place the pumpkin cubes in a pot.

Add 0.2 cups of butter and 1 cup of heavy cream.

Start with 1/4 cup of powdered sweetener, then add 1/4 teaspoon ginger, 1/2 teaspoon allspice, 1/2 teaspoon nutmeg, and 1/2 teaspoon cinnamon. Stir well and bring the mixture to a boil.

In the meantime, take the pie crust out of the oven and set it aside to cool. Note: Simmering the filling on the stove for 20 minutes will enhance its flavor. Ensure not to reduce the simmering time and stir occasionally.

After simmering for 20 minutes, allow the mixture to cool in the pot. Transfer the cooled filling into a bowl.

Blend until it becomes a smooth puree.

Use a clean bowl to crack 2 eggs, whisk well, and then mix into the pumpkin puree. Blend the mixture thoroughly.

Pour this blended filling over the cooled pie crust, spreading it evenly.

Return the pie to the oven and bake for 20 minutes or until the pumpkin layer is firm.

Combine lemon zest with 1.5 cups of heavy whipping cream for the topping.

Dollop 1 tablespoon onto slices of the pumpkin pie before serving.