Ingredients

• 1 teaspoon fennel seeds
• 8 ounces vanilla wafer cookies
• 2 tablespoons all-purpose flour
• 2 tablespoons raw sugar or granulated sugar
• 1 teaspoon Madras curry powder
• 1/4 teaspoon kosher salt
• 6 tablespoons (3/4 stick) unsalted butter, melted, slightly cooled
• 1 envelope unflavored powdered gelatin
• 1 1/2 cups whole milk, divided
• 3 tablespoons granulated sugar
• 1/2 vanilla bean, split lengthwise
• 1 1/2 cups heavy cream
• 3/4 cup (packed) dark brown sugar, divided
• 1/8 teaspoon baking soda
• 3 large egg yolks
• 2 tablespoons cornstarch
• 3 tablespoons unsalted butter
• 1 tablespoon mild-flavored (light) molasses
• 1/2 teaspoon kosher salt
• Unsweetened whipped cream (for serving)
• 1/2 cup chopped salted, dry-roasted cashews

Instructions

1. Place a rack in middle of oven and preheat to 325°F. Toast fennel seeds in a small dry skillet over medium heat, stirring often, until fragrant, about 2 minutes. Transfer to a small plate; let cool, then finely chop.
2. Pulse cookies in a food processor until very fine crumbs form (you should have about 2 cups). Add fennel seeds, flour, raw sugar, curry powder, and salt and pulse to combine. Add butter and pulse until mixture is the consistency of wet sand.
3. Transfer mixture to a 9" pie dish. Using a measuring cup, press firmly onto bottom and up sides of pie dish. Place pie dish on a rimmed baking sheet and bake crust, rotating halfway through, until dry and set, 20–25 minutes. Transfer pie dish to a wire rack and let crust cool.
4. DO AHEAD: Crust can be baked 1 day ahead. Store wrapped tightly at room temperature.
5. For filling and assembly: Place gelatin and 2 tablespoons milk in a small bowl; let stand until gelatin is softened, 5–10 minutes. Place granulated sugar in a medium saucepan; scrape in seeds from vanilla bean and add pod. Cook over medium heat, stirring, until sugar is melted, then cook, stirring occasionally, until mixture turns amber in color, about 3 minutes. Remove from heat and slowly add cream (mixture will bubble vigorously), stirring until smooth. Return to heat and add 1/2 cup brown sugar and remaining milk. Cook, stirring, until sugar is dissolved and caramel mixture begins to steam, about 2 minutes. Remove from heat, add baking soda, and whisk until bubbles subside; remove pod and discard. Whisk egg yolks, cornstarch, and remaining 1/4 cup brown sugar in a medium bowl. Gradually whisk in half of warm caramel mixture. Pour egg-yolk mixture into caramel mixture in saucepan and bring to a boil over medium heat, whisking constantly; reduce heat to low and cook, whisking constantly, until thickened, 2 minutes. Remove from heat and add gelatin mixture, butter, molasses, and salt, whisking until butter is melted and mixture is smooth. Transfer filling to a large bowl and chill, stirring occasionally, until slightly cooled and thickened, about 1 hour. (Stirring and cooling pudding before chilling in crust will give it a luscious, creamy texture.) Pour butterscotch filling into crust, smoothing top if needed. Chill until set, at least 2 hours. Just before serving, spoon whipped cream over pie and top with cashews. DO AHEAD: Pie can be made (without whipped cream) 2 days ahead. Cover and keep chilled.
6. Place gelatin and 2 tablespoons milk in a small bowl; let stand until gelatin is softened, 5–10 minutes.
7. Place granulated sugar in a medium saucepan; scrape in seeds from vanilla bean and add pod. Cook over medium heat, stirring, until sugar is melted, then cook, stirring occasionally, until mixture turns amber in color, about 3 minutes. Remove from heat and slowly add cream (mixture will bubble vigorously), stirring until smooth. Return to heat and add 1/2 cup brown sugar and remaining milk. Cook, stirring, until sugar is dissolved and caramel mixture begins to steam, about 2 minutes. Remove from heat, add baking soda, and whisk until bubbles subside; remove pod and discard.
8. Whisk egg yolks, cornstarch, and remaining 1/4 cup brown sugar in a medium bowl. Gradually whisk in half of warm caramel mixture. Pour egg-yolk mixture into caramel mixture in saucepan and bring to a boil over medium heat, whisking constantly; reduce heat to low and cook, whisking constantly, until thickened, 2 minutes. Remove from heat and add gelatin mixture, butter, molasses, and salt, whisking until butter is melted and mixture is smooth. Transfer filling to a large bowl and chill, stirring occasionally, until slightly cooled and thickened, about 1 hour. (Stirring and cooling pudding before chilling in crust will give it a luscious, creamy texture.)
9. Pour butterscotch filling into crust, smoothing top if needed. Chill until set, at least 2 hours.
10. Just before serving, spoon whipped cream over pie and top with cashews.
11. DO AHEAD: Pie can be made (without whipped cream) 2 days ahead. Cover and keep chilled.