Directions

• First make the crust. Preheat the oven to 195C/175C fan/Gas 5.
• In a food processor, combine the biscuits, demerara sugar, salt, butter and egg yolk and process until the biscuits have broken down into fine crumbs and the mixture looks like moist sand. It should easily hold together when squeezed.
• Transfer just shy of half the mixture to a 20cm removable-bottom tart tin or springform tin. Push the mixture outward to create an even ring around the perimeter, then press the mixture firmly against the sides. Scatter the remaining crumb mixture across the bottom of the tin and use the bottom of a mug or glass to flatten the crumbs into an even layer with no bare spots. Place the tin on a foil-lined baking sheet.
• Bake the crust until it’s fragrant, firm to the touch, and the outer edges are darkened in colour, 13 to 15 minutes. Set aside while you prepare the filling.
• In a small saucepan, combine the orange zest, cinnamon, salt, cranberries, 200g of the granulated sugar, 75g of the pomegranate molasses and 230ml water. Bring the mixture to a boil and cook, stirring often, until the cranberries have burst and the mixture is very thick and reduced to a jammy consistency, 10 to 15 minutes. Remove from the heat.
• Set a fine-mesh sieve over a medium bowl and scrape the compote into the sieve. Set the saucepan aside to use again later. Force the mixture through the mesh using a spatula into the bowl below, pressing on the solids (discard the solids). Whisk 75ml cream into the compote until the mixture is completely smooth. Cover with cling film and refrigerate just until the cranberry mixture is cool, 25 to 30 minutes.
• Rinse and dry the reserved saucepan. Pour 40ml cold water into the saucepan and sprinkle the gelatin over it. Set aside to allow the gelatin to soften, about 10 minutes.
• Meanwhile, whisk 230ml of the double cream to form peaks. Refrigerate the bowl until it’s time to assemble the mousse.
• Remove the cooled cranberry mixture from the refrigerator, uncover, and whisk to smooth it out. Place the saucepan with the gelatin over a low heat and warm, swirling often, until the gelatin is melted into a clear liquid free of granules. Whisk the gelatin into the cranberry mixture.
• Remove the whipped cream from the refrigerator and scrape half of it into the bowl with the cranberry mixture. Fold until just a few streaks remain. Fold in the remaining whipped cream until you have a light, uniform mixture, then scrape into the prepared speculoos crust. Smooth the top and refrigerate until the mousse is set, at least four hours. After the first hour in the refrigerator, cover the pie with cling film to prevent a skin from forming.
• While the pie is setting, in a small saucepan, combine the remaining 100g sugar, 25g pomegranate molasses, and 75ml water. Bring to a very gentle simmer over low heat, stirring to dissolve the sugar, and add the 20 cranberries. Simmer very gently just until the cranberries are softened and a few have burst, about three minutes. With a slotted spoon, remove the cranberries and transfer to a wire rack (discard any that have collapsed or lost their shape). Let sit until the cranberries are slightly tacky to the touch, about one hour. Toss the cranberries in some granulated sugar to coat them and return to the wire rack to continue drying at room temperature until the pie is set.
  
• Just before serving, remove the pie from the refrigerator and uncover. Whip the remaining cream until you have soft peaks. Beat in the powdered sugar and scrape the whipped cream on top of the pie. Spread over the filling, making swooshes and swirls, and dot with the sugared cranberries. Cut into wedges and serve.