260gramsicing sugar, sifted + more as needed, 2 cups
2tsppure vanilla extract
185mlsalted caramel, 3/4 cup
instructions
Make The Apple Cake
Preheat the oven to 350°F (175°C). Prepare three 7- × 2-inch round cake pans by spritzing them with vegetable oil and lining them with parchment paper circles cut to size. Spray again with oil to prevent sticking.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
In the bowl of a stand mixer fitted with the paddle attachment, combine the vegetable oil, applesauce, brown sugar, white sugar, and vanilla extract on medium speed until smooth, about 1 minute.
With the mixer on low speed, add the dry ingredients, mixing until combined, 15–30 seconds. Fold in the grated apple.
Divide the cake batter evenly between the prepared pans. Give the pans a light tap on the counter to reduce any air bubbles. Bake for 22–25 minutes, until the cake edges are lightly browned, the cake springs back to the touch, and a toothpick inserted into the center comes out with only moist crumbs.Let the cakes cool completely in their pans set on top of wire racks.
Make The Salted Caramel
In a heavy-bottomed saucepan, melt the sugar, corn syrup, and water over high heat until the sugar has dissolved. Let the mixture boil without stirring until it reaches a medium amber color, about 10 minutes or so. Remove from the heat and carefully whisk in the plant milk (it will bubble up ferociously, so go slowly). Whisk in the butter, vanilla extract, and salt. Let cool completely; it will thicken as it cools.
Use ¾ cup (185ml) salted caramel for the buttercream (below), and reserve the rest for decorating the cake with caramel drips. Leftover caramel will keep in the fridge for up to 2 weeks—it is delicious drizzled on ice cream or stirred into yogurt.
Make The Oatmeal Cookie Crumbles
Preheat the oven to 350°F (175°). Line a baking sheet with parchment paper.
In a medium bowl, whisk together the sugar, rolled oats, flour, and salt. Sprinkle in the butter, toss to coat, and then mix until well incorporated.
Using a spatula, spread the mixture onto the prepared baking sheet in an even layer. Bake for 18–20 minutes, until golden brown and crisp. Let cool completely in its pan set on top of a wire rack.
Once cooled, break it up into cookie crumbles with your hands or lightly bash them with a rolling pin.
Make The Salted Caramel Buttercream
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, icing sugar, vanilla extract, and ¾ cup (185ml) of the salted caramel on low speed to combine, using a spatula to scrape down the sides of the bowl as needed. Turn the mixer to medium-high speed and beat until light and fluffy, about 1 minute. If the frosting seems too loose, add 1 tbsp of icing sugar at a time to thicken it until it is creamy and spreadable, being careful not to over-sweeten.
Assemble and Decorate The Cake
Frost and fill the cake, using your offset spatula to create a divot or "dug-out pool" in the center of the buttercream to add salted caramel to the cake layers. Frost the exterior of the cake with a thin layer of buttercream and let chill in fridge for 15 minutes.
Remove cake from fridge and apply a second coat. I went with an "au naturel" rustic finish.
Decorate the cake with a piped salted caramel buttercream border on top, or an artful array of piped dollops or drop stars. You can also add drips of salted caramel to the outside of the cake and to the individual cake layers once cut. To preserve maximum crispness, add the oatmeal cookie crumbles in various-sized pieces to the top of the cake just before serving!
notes
This cake will taste freshest enjoyed within a day of making it but can be stored in the fridge, covered, for up to 3 days.