Step 1

Cut 4 tablespoons unsalted butter into small pieces and place in a medium bowl. Let sit at room temperature until softened.

Step 2

Arrange a rack in the middle of the oven and heat the oven to 350ºF. Line a baking sheet with aluminum foil. Break 6 ounces Biscoff cookies into small pieces and place in a food processor fitted with the blade attachment. Pulse into fine crumbs (don’t overprocess or the mixture will be too wet). (Alternatively, crush the cookies in a plastic zip-top bag with a rolling pin.)

Step 3

Transfer the crumbs to the bowl of butter. Add 2 tablespoons demerara sugar, 1 large egg yolk, and 1/2 teaspoon kosher salt. Work the mixture with your fingertips until the butter disappears and the mixture feels like wet sand.

Step 4

Transfer a little less than half of the mixture to a 9-inch removable-bottom round tart pan. Push the mixture outward to create an even ring around the perimeter, then use a straight-sided measuring cup to press the mixture firmly up and against the sides. Scatter the remaining crumb mixture across the bottom of the pan and use the bottom of the measuring cup to flatten the crumbs into an even layer with no bare spots.

Step 5

Place the pan on an aluminum foil-lined baking sheet. Bake until the crust is firm to the touch, and the outer edges are darkened in color, 13 to 15 minutes. Set aside to cool while you make the curd.

Step 6

Place 1/2 cup granulated, 2 large eggs, 2 large egg yolks, and 1/2 teaspoon kosher salt in a small, heavy-bottomed saucepan and whisk vigorously until the mixture is very pale, light in texture, and thick, about 2 minutes.

Step 7

While whisking constantly and scraping around the sides, slowly pour in 1/4 cup lemon juice, 3 tablespoons orange juice, and 3 tablespoons cranberry juice. Whisk until the mixture is smooth.

Step 8

Place over medium-low heat and cook, whisking constantly, until the curd turns opaque, is thick enough to coat the back of a spoon, and barely holds the marks of the whisk (it will also register 170°F on an instant-read thermometer), 7 to 10 minutes. Immediately pour the hot curd into a blender and let cool for a few minutes. Meanwhile, cut 1 stick cold unsalted butter into 1/2-inch pieces.

Step 9

With the blender running on medium-high speed, add the butter one piece at a time until all the butter is incorporated and the mixture is smooth. Add 1 teaspoon vanilla extract, then add 8 ounces cranberry sauce a couple of tablespoons at a time and continue to blend until the curd is completely smooth.

Step 10

Pour the curd into a medium bowl, then place the bowl inside a larger bowl partially filled with ice water. Being careful not to splash any water into the curd, stir constantly with a flexible spatula, making sure to scrape against the sides of the bowl, until the mixture is cool to the touch. Pour the curd into the crust, filling it almost to the top. Refrigerate until completely set, about 3 hours.

Step 11

Pour 1 tablespoon cold water into a small bowl and sprinkle 3/4 teaspoon powdered gelatin over it (don’t stir). Set aside to allow the gelatin to soften, about 10 minutes. Meanwhile, place 6 ounces cranberry sauce, 1/4 cup cup cranberry juice and 1 tablespoon granulated sugar in a small saucepan and warm over low heat, whisking to break up and dissolve the cranberry sauce and sugar.

Step 12

Scrape the gelatin into the saucepan and whisk just until smooth and the gelatin is dissolved. Pour the glaze over the curd. Refrigerate uncovered until the glaze is set, about 2 hours. Cut into slices and serve.