This upside-down cake uses sweet potatoes as the “fruit” and has a base of full-bodied cake that can be enjoyed with a pot of tea by a crackling fire. The caramel sauce may seem ambitious, but all it takes is a candy thermometer and a willingness to watch the pot boil (and be ready to move quickly). 

2 tablespoons softened butter for cake pan 

3/4 cup softened butter 

3/4 cup sugar 

1/4 cup vegetable oil 

2 cups all-purpose flour 

1 teaspoon baking powder 

½ teaspoon baking soda 

1 teaspoon salt 

½ teaspoon allspice 

½ teaspoon ginger 

1 teaspoon finely chopped rosemary 

1 cup toasted pecans 3 eggs 

½ cup buttermilk 

2 tablespoons molasses 

1 tablespoon vanilla 

2 medium sweet potatoes, approx 1/2 pound 

6 tablespoons butter 

½ cup brown sugar 

1 tablespoon water 

1 tablespoon molasses 

Heat oven to 350° F. Line the bottom of a 9-inch cake pan with softened butter and fit in a round of parchment paper. 

In the bowl of a stand mixer, beat butter and sugar until light and fluffy. Add vegetable oil in a thin stream and beat again until incorporated. 

In a separate bowl, combine flour, baking powder, baking soda, salt, allspice, ginger, rosemary, and pecans. 

In a third bowl, combine eggs, buttermilk, molasses, and vanilla and whisk until combined. 

Add 1/3 of the flour mixture to the mixer followed by 1/3 of the egg mixture. Mix until just combined and then repeat until everything is mixed together nicely. Set aside. 

Peel the sweet potatoes and cut them as thinly as possible, preferably with a mandoline. I use a plastic Japanese-style mandoline with a single blade that is both affordable and efficient. 

Melt the 6 tablespoons of butter with the brown sugar, water, and molasses in a small saucepan. Whisk over medium heat until sugar dissolves. Pour the syrup into the bottom of the prepared cake pan. 

Place the thinly sliced sweet potatoes on top of the syrup starting from the middle and working your way to the outside in a concentric circle. 

Spoon the batter on top of the sweet potatoes and bake for 35-40 minutes, until a toothpick inserted into the middle comes out clean. Allow to cool 15 minutes before inverting onto a cake plate. Serve warm with Miso Caramel Sauce. 

MISO CARAMEL SAUCE 

1½ cups white sugar 

1/3 cup water 

1 cup heavy cream, room temperature 

1/4 cup white miso 

In a heavy-bottomed saucepan, add sugar and water. Place over medium-high heat, making sure the heat source is directly below the pan and not extending up the sides, or the caramel will burn. Take a pastry brush dipped in water to push down any sugar that may be clinging to the sides of the pot as the caramel starts to form. 

The water will soon evaporate, and there will be only sugar cooking, so keep your eye on it. Don’t stir. If the color starts to look uneven, you can gently swirl the pot. Once you notice color, things will happen fast, so be ready to remove the caramel from the heat. 

A medium dark caramel is about 365° F on a candy thermometer. Take the caramel off the heat at around 360° F as it will keep cooking. Allow it to settle down for a few seconds and add the cream. Be careful, as it might splutter. Once the sauce has calmed down, whisk in the miso until it is smooth. 

If made ahead, this sauce can be rewarmed gently while stirring.