This unique & delicious cheesecake recipe comes from Sawako Okochi & Aaron Israel's beautiful new cookbook Love Japan.
"It's common to use sweet potatoes in desserts in Japan. There's one that in Japanese is called simply sweet potato, a baked mixture of mashed sweet potatoes, sugar, butter, and cream. That's what this cheesecake reminds me of. Sweet potatoes add body and earthy flavor to the filling, and complement the nutty sesame crust. It's less rich and sweet than your classic cheesecake, but still luxurious. If you can't find satsumaimo (Japanese sweet potatoes), just use the American kind. The batter will be slightly wetter, so add an extra teaspoon of cornstarch to achieve the right consistency."
560g (20 ounces) Japanese sweet potatoes (about 2), washed (we used purple sweet potatoes)
Softened butter, for the pan
For the Sesame Crust
140g graham crackers (nine 5 x 2½-inch graham crackers; 1 sleeve from a 14.4-ounce box)
80g (6 tablespoons) unsalted butter, melted
20g (1 tbsp plus 2 tsp) Seed + Mill Organic Tahini
2 tsp sugar
¼ tsp kosher salt
For the Batter
180g (3/4 c) whole-milk ricotta
40g (1½ ounces) cream cheese, at room temperature
100g (½ c) sugar
100g (½ c) sour cream
2 tsp cornstarch
2 large eggs
2/3 c heavy cream
1/8 tsp ground cinnamon
Finely grated zest of ½ lemon
¼ tsp vanilla extract
Lightly sweetened whipped cream or crème fraîche, for serving
Preheat the oven to 375°F.
Wrap each sweet potato tightly in foil and bake until fork-tender, 1½ to 2 hours, turning halfway through. Cool for about 15 minutes. Unwrap and peel the sweet potatoes, then mash in a small bowl. Measure out 400g (1½ cups) and set aside.Save the rest for another use. Leave the oven on.
Generously butter a 9-inch springform pan. Line the bottom with a round of parchment paper, smoothing it so it sticks. Wrap the outside of the pan with foil to prevent water from seeping in while it bakes in the water bath, Set aside.
To make the sesame crust: In a food processor, pulse the graham crackers a few times until the consistency of cornmeal. In a small bowl, mix the melted butter and kuro neri goma. Pour into the food processor, pulsing a few times to incorporate. Add the sugar and salt and pulse a few times to combine.
Transfer the graham cracker mixture to the prepared springform pan. Using your fingers, push the crumbs firmly into the bottom of the pan, creating an even thickness. The crust can be made and refrigerated up to 1 week ahead, or frozen for up to 2 months.
To make the batter: In a food processor, process the ricotta and cream cheese until smooth, about 1 minute. Add the sugar, pulse for 30 seconds, scrape down the sides with a spatula, and process for another minute. Add the sour cream and cornstarch, pulse for 30 seconds, then process for 1 minute. Add the eggs and process until incorporated, about 1 minute. Add the mashed sweet potato and process until fully blended, I to 2 minutes, scraping down the sides of the bowl once or twice. Add the heavy cream, cinnamon, lemon zest, and vanilla and blend until incorporated.
Pour the batter through a fine-mesh sieve over a large bowl (it should look like a thin pancake batter), pushing it through with a spatula. Pour into the crust, smooth out the top with a spatula, and gently rap on the counter to get out any air bubbles. Place in a large roasting pan and set both on a pulled-out rack in the oven. Pour boiling water into the roasting pan to come halfway up the sides of the springform pan.
Bake for 25 minutes. Rotate the pan front to back and bake until a skewer inserted in the center comes out clean, 25 to 30 minutes longer. Remove from the oven, taking care not to splash the water. Transfer the cheesecake to a cooling rack, remove the foil, and let cool to room temperature. Cover and refrigerate overnight to set.
When ready to serve, unmold the cake, slice, and serve with whipped cream