3cupschopped apples(about 3 small apples, peeled, cored, and cut into ¼-inch pieces/400g chopped)
For the Caramel Topping:
½cuppacked light brown sugar(110g)
2tablespoonsunsalted buttersoftened
¼cupheavy cream(120ml)
1teaspoonvanilla extract
¼teaspoonsalt
For the Frosting:
¾cupunsalted buttersoftened (170g)
½teaspooncinnamon
1poundpowdered sugar(450g)
⅓cupheavy cream(80ml)
2teaspoonsvanilla extract
Instructions
For the Cake:
Preheat the oven to 350°F. Grease three 6-inch cake pans and line the bottoms with parchment paper.
In a large bowl, whisk together the flour, cinnamon, salt, nutmeg, baking powder, and baking soda. In a medium bowl, whisk together the sugars, vegetable oil, eggs, and vanilla extract until well combined. Pour the wet ingredients into the dry ingredients and stir together until almost combined. Add the apples and stir until they are well distributed and all of the flour has been mixed in. (The batter will be thick.) Divide the cake batter among the prepared pans and spread it into an even layer.
Bake for 40 to 45 minutes or until a toothpick inserted into the center of each cake comes out clean. Let the cakes cool in the pan for 10 minutes, then remove them and cool completely on a wire rack.
For the Caramel Topping:
Combine the brown sugar, cream, and butter in a medium saucepan and place over medium heat. Bring to a boil, stirring occasionally. Boil until the caramel reaches 230°F, about 1 minute. Remove from the heat and whisk in the vanilla and salt. Let the sauce cool completely.
For the Frosting:
Combine the butter and cinnamon in a large mixing bowl if using an electric hand mixer or the bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed until creamy, about 30 seconds.
With the mixer on low speed, gradually add in the powdered sugar, ½ cup at a time, alternative with a small pour of the cream, until both are fully incorporated. Stop and scrape down the bowl occasionally.
Add the vanilla and increase the speed to medium. Beat until fluffy, about 1 minute.
For the Assembly:
Place a cake layer on a cake stand or serving plate. Spread ½ cup of frosting over the top of the layer and drizzle with 1 tablespoon of caramel. Place another cake layer on top and repeat with the frosting and caramel. Place the last layer on top and spread the remaining frosting all over the top and sides of the cake. Chill for 30 minutes to set the frosting.
Spread the caramel on top of the cake, pushing it to the sides to drip off, if desired. Refrigerate for at least 10 minutes to set the caramel before serving. Store the cake covered and refrigerated for up to 5 days.
Notes
Weigh the flour: Using a kitchen scale is the most accurate way to measure flour. If you don't have one, fluff the flour up in its container, spoon it into a measuring cup, and level off the top with a knife.
Don't over-mix the batter, or you'll end up with a tough cake caused by gluten overdevelopment.
Add more spices to the cake. You can add up to ½ teaspoon each of ground ginger, ground allspice, and ground cardamom to the cake layers.
Use browned butter for the frosting. Follow my guidelines for how to brown butter and cool it until softened. Beat it with the powdered sugar according to the recipe.
Add caramel to the frosting. If desired, you can beat in 3 tablespoons of caramel sauce for extra caramel flavor.
Leftover caramel sauce ideas: Use it to serve with each slice of cake, drizzle it over vanilla ice cream, or stir it into coffee.