Sweet Potato Mousse Cake Recipe

Prepare pan and crumbs

Preheat oven to 350°F (175°C). Lightly butter and line the bottom of a 9-inch (23 cm) springform pan with parchment paper.

Place gingersnap cookies in a food processor and pulse to fine crumbs (about 2 cups). If you don't have a processor, place cookies in a zip-top bag and crush with a rolling pin.

Combine the cookie crumbs, melted butter, granulated sugar, and 1/8 tsp salt in a bowl; mix until crumbs are evenly moistened and hold together when pressed.

Press the crumb mixture evenly into the bottom (and about 1/2 inch up the sides if desired) of the prepared springform pan using the bottom of a measuring cup or glass to compact firmly.

Bake the crust for 8–10 minutes, or until fragrant and set. Remove from oven and cool on a rack while you make the mousse. Reduce oven to 325°F (160°C) if you plan to use oven for any component; otherwise you can keep it off.

Prepare sweet potato purée (if not prepared)

If you don't have cooked purée, pierce 2 medium-large sweet potatoes and roast at 400°F (200°C) for 45–60 minutes until very tender. Scoop flesh and mash or process until smooth. Measure 2 cups purée and let cool to warm (not hot).

In a small bowl sprinkle 1 1/2 tsp granulated gelatin over 3 tbsp cold water. Let bloom for 5–7 minutes until spongy.

Place 1 cup whole milk, 2 tbsp sugar (from the 1 cup) and 2 tbsp unsalted butter in a small saucepan over medium heat. Stir until sugar dissolves and butter melts; heat until just simmering, then remove from heat.

Whisk the bloomed gelatin into the hot milk mixture until fully dissolved. Allow the mixture to cool slightly (about 2–3 minutes) so it is warm but not hot.

In a medium bowl combine the sweet potato purée, remaining sugar (about 14 tbsp — note: the ingredient list shows 1 cup; use a total of 1 cup sugar distributed as 2 tbsp for milk heating and the remainder folded into purée), vanilla extract, ground cinnamon, ground nutmeg, and 1/4 tsp salt. Stir until smooth and combined. If the purée is very thick, add up to 2 tbsp additional milk to loosen slightly.

Temper about 1/3 cup of the sweet potato mixture into the warm milk-gelatin mixture by whisking it in quickly, then pour that back into the bowl with the rest of the sweet potato mixture and whisk until homogeneous and slightly glossy.

In a chilled bowl, whip 1 cup heavy cream with an electric mixer to soft peaks. Sweeten lightly if desired (up to 1 tbsp sugar) but not required because mousse already contains sugar.

Fold one-third of the whipped cream into the sweet potato base to lighten it, then gently fold in the remaining whipped cream in two additions until no streaks remain. Use gentle folding motions to preserve air; do not overmix.

Pour or spoon the finished mousse over the cooled gingersnap crust in the springform pan, smoothing the top with an offset spatula. Tap the pan gently on the counter to remove any air pockets.

Chill the assembled cake in the refrigerator for at least 4 hours, preferably 6–8 hours or overnight, until the mousse is fully set.

Run a thin knife around the edge of the pan to loosen, then release the springform. Transfer the cake to a serving plate if desired.

Optional: Lightly dust the top with 2 tbsp powdered sugar, scatter 1/2 cup toasted chopped pecans around the edge, and pipe or spoon 1/2 cup whipped cream dollops for garnish.

Slice with a sharp knife dipped in hot water and wiped dry between cuts for clean slices. Serve chilled. Keeps refrigerated up to 3 days; garnish just before serving.