PUMPKIN CHIFFON SLAB PIE

Steps:

• Preheat the oven to 350 degrees F (175 degrees C). Set a baking stone, baking steel, or inverted baking sheet on the center rack.
• Stir together crushed amaretti, butter, and salt in a bowl with a firm spatula, pressing mixture against bowl until well combined. Dump into a 9x13-inch quarter-sheet pan or a 9x13-inch baking pan. Pat and press mixture along sides and bottom of pan. Use a metal measuring cup to compact mixture for a smooth, firm crust.
• Bake crust on top of hot stone until lightly browned, 15 to 20 minutes.
• Meanwhile, for the filling, sprinkle gelatin over cool water in a small bowl and let stand. Fill a large bowl with ice water to make an ice bath.
• Fill medium saucepan halfway with water and bring to a simmer over medium-high heat.
• Whisk pumpkin, egg yolks, brown sugar, cinnamon, vanilla, salt, allspice, and cloves together in a large heatproof bowl until well combined. Set bowl over, but not touching the simmering water.
• Cook, stirring constantly with a rubber spatula, until mixture registers 170 degrees F (86 degrees C), about 10 minutes. Remove from heat, add gelatin mixture, and stir until melted. Set bowl over ice bath and whisk as it cools to slightly warmer than room temperature, about 85 degrees F (29 degrees C). Remove from ice bath.
• Whip egg whites in a large bowl with a hand mixer set on high until frothy. Add cream of tartar and continue whipping until whites are shiny and medium peaks form, another 3 or 4 minutes. Add 1/3 to the pumpkin mixture; stir until incorporated and mixture is lightened. Gently fold in remaining whites with a rubber spatula until no large white streaks remain. Pour into the cooled crust.
• Chill, covered, until firm, about 4 hours.
• Whip cream with a hand mixer in a large bowl, increasing speed as soft peaks form. Add confectioners' sugar, 1 tablespoon at a time, beating until whisk leaves a trail and forms firm peaks when lifted.
• Spoon cream into a piping bag with an open tip or a zip-top plastic bag with a 1/2-inch corner snipped off. Pipe dollops of varying sizes over pumpkin filling, allowing some filling to show through. Dust with cinnamon. Cut into squares.