- 1 1/4 cups skin-on hazelnuts
- 1 cup all-purpose flour
- 2 tablespoons granulated sugar
- 3/4 teaspoons kosher salt
- 1/2 cup (1 stick) chilled unsalted butter, cut into pieces
- Pinch of cream of tartar
- 1 1/4 cups granulated sugar, divided
- 1 cup heavy cream
- 1 cup canned pumpkin purée
- 2 tablespoons light brown sugar
- 1 tablespoon all-purpose flour
- 1 1/2 teaspoons finely grated peeled ginger
- 3/4 teaspoon ground cinnamon
- 3/4 teaspoon kosher salt
- 3 large eggs
- Whipped cream (for serving)
- A 9″ springform pan
- Preheat oven to 350°F. Toast hazelnuts on a rimmed baking sheet, tossing once, until fragrant and slightly darkened, 8–10 minutes; let cool. Using a kitchen towel, rub hazelnuts together to remove most of the skins (don't worry about some stubborn bits remaining).
- Pulse flour, sugar, salt, and 3/4 cup hazelnuts in a food processor until the consistency of coarse meal. Reserve remaining 1/2 cup hazelnuts for filling. Add butter to dry ingredients and pulse until there are only a few pea-size pieces of butter remaining.
- Transfer mixture to a large bowl; drizzle 3 Tbsp. ice water over and mix, adding another splash or so of water if needed, just to bring dough together.
- Using your fingers, press dough evenly 1 1/2″–2″ up the sides and then into the bottom of pan; compact and smooth with a flat, straight-sided measuring cup or glass. Chill 20 minutes.
- Bake crust until golden but not totally baked through, 15–20 minutes. Transfer to a wire rack and let cool 10 minutes.
- Meanwhile, bring cream of tartar, 1 cup granulated sugar, and 2 Tbsp. water to a boil in a medium saucepan over medium heat, stirring until sugar dissolves. Increase heat to mediumhigh and cook, swirling pan occasionally (do not stir), until caramel is a deep amber color, 8-10 minutes. Remove from heat. Whisking constantly, carefully add cream (mixture will be extremely hot and will bubble vigorously); whisk until smooth. Let caramel cool slightly in pot.
- Whisk pumpkin purée, brown sugar, flour, ginger, cinnamon, and salt in a large bowl. Gradually add caramel and eggs, whisking until well blended. Scrape filling into prepared crust.
- Bake tart, rotating halfway through, until filling is set around edges and center barely jiggles, 30-35 minutes. Transfer to a wire rack and let cool in pan.
- Meanwhile, coarsely chop reserved 1/2 cup hazelnuts and cook in a small skillet over medium heat with remaining 1/4 cup sugar and 1 Tbsp. water, stirring constantly, until sugar caramelizes and evenly coats hazelnuts. Transfer caramelized hazelnuts to a sheet of parchment paper and let cool completely. Coarsely chop. Scatter caramelized hazelnuts over tart and serve with whipped cream.
- Tart (without nuts) can be made 2 days ahead; cover and chill. Hazelnuts can be caramelized 2 days ahead; store airtight at room temperature.