Walnut Crust, fully baked in a 10-inch fluted loose bottom tart pan and cooled
Filling:
1 ½ cups heavy cream, divided
⅔ cup sugar
5 large egg yolks
1 cup plus 2 tablespoons canned pumpkin purée
2 tablespoons bourbon or rum
1 ¼ teaspoons pumpkin pie spice
½ teaspoon vanilla extract
Pinch of salt
Topping:
¾ cup chilled heavy cream
1 ½ tablespoons sugar
Pastry bag and star tip such as a Wilton 1M
Pumpkin pie spice
Instructions
For the Mousse: Make sure crust is baked and cooled and ready to fill. Whisk together ¾ cup of cream, sugar, and egg yolks in heavy saucepan. Cook over medium-low heat, whisking often, until thickened to a pudding consistency. Transfer mixture to large bowl. Whisk in pumpkin, bourbon, pumpkin pie spice, vanilla and salt. Chill until cool to the touch, about 30 minutes.
Whip remaining ¾ cup cream in a clean bowl until soft peaks form. Fold whipped cream into pumpkin mixture and scrape into prepared crust, smoothing top with a small offset spatula. If you want to freeze for up to 3 days, leave it ungarnished and freeze it at this point. Once firm, you can cover with plastic wrap.
For the Topping: At least 6 hours before serving or up to 1 day ahead, unmold the tart and apply the topping. The pan might be frozen to the crust. To unmold, soak a clean kitchen towel in hot water, wring it dry and wrap it around the outside of the tart pan. Alternately I have used a propane torch (carefully) to warm the metal. The tart should unmold easily. Place on a display platter. Whip the cream and sugar until slightly firm peaks form. Scrape into pastry bag fitted with tip and pipe decorative pattern (I did a lattice). Freeze tart at least 6 hours or overnight. Right before serving sprinkle with extra pumpkin pie spice. Serve immediately.
Recipe by Bakepedia at https://www.bakepedia.com/frozen-pumpkin-spice-latte-mousse-tart/