I decided to try the recipe with apples tossed in honey, lemon juice and cinnamon. It came out great but on the sweeter side, so I'd suggest using sour green apples, or the plums called for in the recipe of origin, if you make it.
Here's the recipe. Tell me how it comes out for ya!
Sour Apple Torte
1 cup all-purpose flour
1 teaspoon baking powder
1/4 teaspoon table salt
2/3 cup granulated sugar
1/2 cup unsalted butter, room temperature
2 large eggs
4 small sour apples, peeled, cored and sliced thinly
1 Tablespoon freshly squeezed lemon juice
1 teaspoon ground cinnamon
1 Tablespoon honey
1/4 cup sliced almonds, optional
Preheat your oven to 350. Grease an 8 or 9 inch springform pan (both sizes work great just check on the large pan on the earlier side) and set it on a baking sheet.
Prep the apples by peeling, coring, halving, then slicing, as pictured above, like a hasselback potato. Mix together the lemon juice, honey and cinnamon and drizzle over the apples to coat them while trying not to separate the slice bundles.
In a separate bowl, whisk together the flour, baking powder and salt.
In the bowl of a mixer, or with an electric handheld, cream the butter and sugar for about 4 minutes until light and fluffy. Add the eggs, mixing for another minute. Add the dry to the wet and mix until just combined.
Use a spatula to transfer the batter (mine is always very thick) to your prepared pan and smooth it out to the edges. An offset spatula makes easy work of this.
Nestle the apples around the edge and then center of the pan, leaving about a half-inch from the edge and each other, around each bundle. Drizzle any remaining honey/cinnamon/lemon juice mixture over the cake batter and apples.
*I found that this is especially important if you are using plums because they basically melt leaving cavities in the cake, so moving them in a smidge from the edge of the pan helps to keep the your cake intact.
Sprinkle the top of the cake with the almonds and bake for about 45-50 minutes until it passes the toothpick test.
I like this cake when it's warm best (with either plums or apples) despite it being generally recommended at room temp on the second day. Enjoy!