In a medium bowl, mix together pecans, cinnamon and sugar. Melt butter and add to pecan mixture. Once all has been incorporated, pour into pie/tart pan and press into sides and bottom. Refrigerate for one hour.
Preheat oven to 350 degrees.
Bake crust for 10-15 minutes. Remove and let cool on wire rack for at least 30 minutes. Now it's ready to fill!
Place orange juice or apple cider in a small bowl. Sprinkle gelatin over top and let sit.
In a medium saucepan, whisk pumpkin, milk, light brown sugar, egg yolks and spices, over medium heat. Cook, stirring constantly, for about 9 minutes or just until mixture starts to steam. If you have a thermometer, cook until reaches 160 degrees.
Remove from heat and add in gelatin mixture and stir until dissolved. Pour into a large bowl and let cool for 15 minutes.
In an electric mixer, whisk egg whites on high speed until medium peaks form. Add sugar slowly and continue to beat until stiff peaks form.
Fold half of egg whites into pumpkin mixture, stirring to combine. Add remaining egg whites and carefully fold in until no white streaks remain.
Cinnamon Whipped Cream
Place bowl and beaters in freezer for about 10 minutes. Pour cream into bowl and start mixer. Slowly add remaining ingredients and beat until stiff peaks form.
Pour chiffon into cooled pie crust and level off top. Note: Not all filling will fit into tart pan as it depends on the size of your pan. I had extra, so I filled two smaller dishes to have for a trifle or to eat "as is".
Place in refrigerator and let set overnight. When ready to serve, lift out of tart pan and decorate with cinnamon whipped cream or prepared whipped cream in a can. *Do not decorate with whipped cream until ready to serve.
You can also make this in a springform pan. If using this type of pan, all the filling will fit.