Jelly Doughnut Cake

Preheat the oven to 375°F with a rack in the center. 

To prepare the pan: Line the bottom of a 9" round pan with parchment. In a small bowl, combine the olive oil and melted butter, then brush the bottom and sides of the pan with about half of the mixture. Sprinkle the pan with 1 tablespoon of the granulated sugar, then shake and tilt the pan so that it’s evenly coated. (Reserve the remaining ingredients for coating the baked cake.) 

To make the jam filling: In a small bowl, stir together the raspberry preserves and flour. Set aside. 

To make the cake: In a large bowl, whisk the butter and olive oil until combined. Add the eggs and whisk vigorously until the mixture is homogeneous and shiny. Whisk in the sugar until well combined, then whisk in the sour cream and vanilla until no lumps remain. 

Add the baking powder, salt, and baking soda and whisk until dissolved. Add the flour and whisk until no dry spots remain; the batter will be thick. 

Transfer about two-thirds of the batter (about 2 1/2 cups or 600g) to the prepared pan and smooth it into an even layer. Spoon the jam into the center and spread it into a round, leaving a 1" border of uncovered batter around the edge. Dollop the remaining batter over the top of the jam, then use a flexible spatula or a small offset spatula to smooth the batter into a thin, even layer, covering the jam as best as you can. (Try not to disturb the jam, but a small amount of mixing is OK.) 

Bake the cake for 32 to 38 minutes, until it’s deep golden brown, well risen, and starting to pull away from the sides of the pan; a toothpick inserted into the cake should come out clean. Remove the cake from the oven and transfer the pan to a wire rack.  

While the cake is still hot, run a dull knife around the edges of the pan to release any sticky jam. 

Let the cake cool in the pan for 10 to 15 minutes, then turn it out onto a wire rack. Brush the surface of the cake with the remaining olive oil and melted butter mixture, then sprinkle the remaining granulated sugar over the top. Let the cake cool completely before slicing.

To finish: Lightly score the cool cake into as many slices as you’d like (10 to 12), then use a chopstick to make a small hole in the side of what will become each slice. Fit a piping bag fit with a small tip, then add the jam to the bag. Pipe a little jam into each hole so that it dribbles out slightly, akin to the filling of a jelly doughnut. 

Dust the cake generously with confectioners’ sugar, then slice it so that each piece has a jam hole. 

Storage information: Store the Jelly Doughnut Cake airtight at room temperature for several days. Confectioners’ sugar will dissolve into the cake, whereas Snow White Non-Melting Topping Sugar will maintain its appearance.