In a pot over low heat, mix together pumpkin puree, orange zest, and orange juice. Cook for 2-3 minutes. Add orange extract, vanilla extract, and cinnamon. Stir and cook for about 5 minutes. Add white chocolate chips and stir until chocolate melts and blends with other ingredients. Add gelatin powder. Stir carefully to ensure there are no lumps and set aside to cool. Once cooled, add cream cheese and mix with a mixer.
Line an 8-inch diameter round pan (preferably with a removable bottom) with parchment paper. In a double boiler, melt the chocolate, adding 3-4 tablespoons of milk and mixing to combine. Set aside until cool enough to handle.
Crumble the graham crackers and walnuts in a blender or with a rolling pin. Incorporate the melted chocolate, mixing thoroughly until the mixture reaches a batter-like, slightly gooey texture (it should be easy to handle – if it’s too sticky, add more graham crackers). Transfer the mixture into the prepared pan, and line the edges and bottom of the pan with it, pressing with your hands.
Top the chocolate layer with the pumpkin filling and spread it evenly over the surface. Cover and place in the refrigerator for 3 hours.
Remove the pie from the refrigerator. Mix apricot jam with hot water in a small bowl. Arrange the orange slices on top of the pie, and spread a thin layer of the jam mixture over the whole pie (the most convenient way to do this is with a pastry brush). Sprinkle the pie with walnuts. Cover and place back in the refrigerator for at least 3 hours. Serve cold.