Ingredients

For the pie crust:

• 1 (8.8-ounce) package Biscoff cookies (31 cookies, see Recipe Notes)
• 3 tablespoons granulated sugar
• 3/4 teaspoon kosher salt
• 6 tablespoons (3/4 stick) unsalted butter, melted

For the filling:

• 1/4 cup water
• 1 (1/4-ounce) envelope unflavored gelatin
• 3 large egg yolks
• 1/3 cup granulated sugar
• 1/2 cup whole or 2% milk
• 1 teaspoon Pumpkin Pie Spice, plus more for dusting
• 1 1/2 teaspoons vanilla extract
• 1 (15-ounce) can pumpkin purée (not pumpkin pie mix)

For the meringue:

• 3 large egg whites
• 1/2 cup granulated sugar
• 1/4 teaspoon cream of tartar
• 1/4 teaspoon kosher salt

For the whipped cream:

• 1 1/4 cups cold heavy cream
• 3 tablespoons granulated sugar
• 2 teaspoons vanilla extract

1. Heat the oven to 350°F.
2. Process 1 (8.8-ounce) package Biscoff cookies, 3 tablespoons granulated sugar, and 3/4 teaspoon kosher salt together in a food processor until the cookies are the texture of sand, 20 to 30 seconds. Drizzle 6 tablespoons melted unsalted butter over the crumbs and pulse until evenly combined and starting to clump, 20 to 30 seconds.
3. Transfer into a 9 1/2-inch deep-dish pie pan and press evenly into the bottom and up the sides.
4. Bake until the crust is darkened slightly and become fragrant, 12 to 15 minutes. Place on a wire rack and let cool while you make the filling.
5. Make the filling:
6. Place 1/4 cup water in a small bowl. Sprinkle 1 (1/4-ounce) envelope unflavored gelatin over the water and stir to combine. Let sit for at least 5 minutes to bloom.
7. Meanwhile, whisk 3 large egg yolks, 1/3 cup granulated sugar, 1/2 cup whole milk, 1 teaspoon pumpkin pie spice, and 1 1/2 teaspoons vanilla extract together in a small saucepan. Cook over medium heat, whisking continuously, until slightly thickened, about 4 minutes.
8. Reduce the heat to low. Whisk in the bloomed gelatin until smooth, 30 seconds to 1 minute. Transfer to a medium bowl. Whisk in 1 (15-ounce) can pumpkin purée until smooth.
9. Fill a large bowl halfway with ice and water. Nestle the bowl of filling into the ice water bath, being careful not to get any water into the pumpkin mixture. Stir occasionally while you make the meringue.
10. Make the meringue:
11. Fill a small saucepan with an inch or two of water (make sure the bottom of a medium heatproof bowl does not touch the water when placed onto the saucepan). Bring the water to a simmer over medium heat. Reduce the heat as needed so it maintains a gentle simmer.
12. Place 3 large egg whites, 1/2 cup granulated sugar, 1/4 teaspoon cream of tartar, and 1/4 teaspoon kosher salt in a medium heatproof bowl. Fit the bowl onto the saucepan and cook, stirring continuously with a flexible spatula, until the mixture registers 175°F and is white, frothy, and thickened, 5 to 12 minutes.
13. Scrape the mixture into a stand mixer bowl. Beat with the whisk attachment on medium-high speed until glossy, medium peaks form, 2 to 3 minutes.
14. Assemble the pie and make the whipped cream:
15. Remove the pumpkin mixture from the ice water bath. Gently fold the meringue into the pumpkin mixture until just combined. Transfer to the pie crust and spread into an even layer. Refrigerate until set, at least 5 hours and up to overnight.
16. When ready to serve, beat 1 1/4 cups cold heavy cream, 3 tablespoons granulated sugar, and 2 teaspoons vanilla extract together in a stand mixer fitted with the whisk attachment on medium-high speed until medium peaks form, 2 to 3 minutes.
17. Spread over the pie in swooping motions. Dust with pumpkin pie spice if desired and serve.